LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 

©IFT    OF 

Class 


GENERAL 


MEDICAL    CHEMISTRY 


FOB  THE    USE   OP 


PRACTITIONERS    OF    MEDICINE 


BY 

E.   A.   WITTHAUS,  A.M.,   M.D., 

Professor  of  Chemistry  and  Toxicology  in  the  Medical  Department  of  the  University  of  Vermont;   Pro- 
fessor of  Physiological  Chemistry  in  the  Medical  Department  of  the  University  of  the  City  of 
New  York  ;  Member  of  the  Chemical  Societies  of  Paris  and  Berlin  ;  Fellow  of  the  New 
York  Academy  of  Medicine  and  of  the  American  Academy  of  Medicine,  etc. 


NEW  YORK 

WILLIAM    WOOD    &    COMPANY 
27  GKEAT  JONES  STREET 

1881 


COPTRIOHT 

WILLIAM   WOOD  &  COMPANY 

1881 


TROW'S 

PRINTING  AND  BOOKBINDING  COMPANY 

201-213  East  izth  Street 

NKW  YOKK 


PREFACE 


Lsr  the  arrangement  of  this  work,  it  has  been  deemed  advisable  to 
depart,  in  certain  points,  from  the  methods  usually  followed  in  chemi- 
cal text-books.  Those  portions  treating  of  technical  processes  have 
been  condensed  to  a  minimum,  while  the  bearings  of  chemistry  upon 
physiology,  hygiene,  therapeutics,  and  toxicology,  have  been  treated  of 
as  fully  as  the  limits  of  the  work  have  permitted.  The  division  of  the 
elements  into  metals  and  metalloids  has  been  abandoned  as  unscientific, 
and  a  classification  has  been  adopted  which  the  author  believes  to  pos- 
sess advantages  over  those  hitherto  followed,  especially  in  that  it  is 
based  upon  purely  chemical-  characters. 

Organic  chemistry  has  not  been  considered  as  a  distinct  division  of 
the  subject,  but  simply  as  the  chemistry  of  the  compounds  of  carbon ; 
an  arrangement  not  only  logical,  but  sanctioned  by  the  works  of  Feser, 
Schiitzenberger,  and  others.  The  classification  of  the  carbon  com- 
pounds is  based,  as  far  as  possible,  upon  their  relations  to  the  different 
series  of  hydrocarbons. 

The  size  of  the  volume  being  limited,  the  author  has  preferred  to 
abstain  from  the  use  of  illustrations,  thinking  that  the  space  could  be 
better  utilized  as  it  has  been.  Through  mistake  of  the  printer  in 
casting  up  the  copy,  he  has  also  been  obliged  to  condense  that  portion 
of  the  work  treating  of  the  third  and  fourth  classes  of  elements 
more  than  he  wished,  and  quite  out  of  proportion  to  the  rest  of 
the  work. 

It  is  hardly  necessary  to  state  that  the  modern  system  of  notation 
has  been  followed.  All  weights  and  measures  are  given  in  the  metric 
system,  and  temperatures  in  degrees  of  the  Centigrade  scale. 

E.  A.  W. 

766  MADISON  AVENUE,  NEW  YORK, 
August  7,  1881. 

218871 


CONTENTS. 


INTRODUCTION. 

PAGE 

General  properties  of  matter 2 

Elements  and  compounds 7 

Laws  governing  the  combination  of  elements 7 

The  atomic  theory 8 

Atomic  and  molecular  weights 11 

Symbols,  formulas,  equations 16 

Radicals,  acids,  bases,  salts 17 

Nomenclature 20 

Oxides,  hydrates,  and  chlorides 23 

Typical  formulae  and  formulas  of  constitution 23 

Classification  of  elements 26 

Physical  characters  of  chemical  interest 28 


SPECIAL  CHEMISTEY. 

Elements  of  Class  1 33 

Hydrogen 33 

Oxygen. . : 35 

Ozone 37 

Water 37 

Elements  of  Class  TL 09 

CHLORINE  GROUP 69 

Fluorine 69 

Chlorine 70 

Bromine 77 

Iodine. .  78 


vi  CONTENTS. 

PAGE 

SULPHUR  GROUP 82 

Sulphur 82 

Selenium  and  tellurium 93 

NITROGEN  GROUP ;"1 94 

Nitrogen 94 

Air 95 

Phosphorus 106 

Arsenic , 116 

Antimony 131 

BORON  GROUP 139 

Boron 139 

CARBON  GROUP. 141 

Carbon 141 

Classification  of  carbon  compounds „ 148 

First  series  of  hydrocarbons 157 

Second  series  of  hydrocarbons 227 

Third  series  of  hydrocarbons 287 

Fourth  series  of  hydrocarbons 292 

Fifth  series  of  hydrocarbons 315 

Sixth  series  of  hydrocarbons 334 

Seventh  series  of  hydrocarbons 336 

Eighth  series  of  hydrocarbons 336 

Ninth  series  of  hydrocarbons 337 

Tenth  series  of  hydrocarbons 337 

Eleventh  series  of  hydrocarbons 337 

Higher  series  of  hydrocarbons 338 

Cyanogen  compounds 342 

Glucosides 342 

Alkaloids 346 

Albuminoids 360 

Animal  ferments 368 

Animal  coloring  matters 369 

Silicon 372 

MOLYBDENUM  GROUP 373 

Elements  of  Olasa  III 374 

GOLD  GROUP 374 

IRON  GROUP 374 

Chromium 375 

Manganese 376 

Iron 377 

ALUMINIUM  GROUP 381 

Aluminium .  381 


CONTENTS.  Vll 

PAGE 

LEAD  GROUP 384 

Lead .' 384 

BISMUTH  GROUP 388 

Bismuth 388 

TIN  GRO  UP 390 

Tin 390 

PLATINUM  AND  RHODIUM  GROUPS— 392 

Platinum 392 

Elements  of  Class  IV 393 

SODIUM  GROUP 393 

Lithium. 393 

Sodium 394 

Potassium 399 

Silver 407 

Ammonium 408 

CALCIUM  GROUP 411 

Calcium 411 

Barium 415 

MAGNESIUM  GROUP 416 

Magnesium 416 

Zinc 418 

NICKEL  GROUP 419 

Nickel 419 

Cobalt 419 

COPPER  GROUP 420 

Copper 420 

Mercury 423 


GENERAL 

MEDICAL    CHEMI8TET. 


Part  1. 

INTRODUCTION. 


IT  is  difficult  to  give  at  the  outset  a  clear  and  concise  idea  of  what 
is  understood  as  chemical  science.  The  best  and  simplest  definition  of 
chemistry  is  a  modification  of  that  given  by  Webster:  That  branch  of 
science  which  treats  of  the  composition  of  substances,  their  changes  in 
composition,  and  the  laws  governing  such  changes.  It  will  be  seen  that 
the  essential  character  of  the  science  is  that  it  has  to  deal  with  composi- 
tio?i,  and  in  this  the  line  between  physical  and  chemical  phenomena  is  more 
sharply  drawn  than  that  between  the  individual  varieties  of  the  former. 

A  bar  of  soft  iron  is  the  same  in  composition,  whether  it  be  hot  or 
cold,  luminous  or  non-luminous,  magnetized  or  not  magnetized.  When, 
however,  it  comes  under  the  dominion  of  chemical  action,  its  composition 
is  changed,  and,  although  the  resulting  substance  contains  iron,  it  differs 
in  its  appearance  and  properties  from  that  metal.  Moreover^  this  change 
in  composition,  once  brought  about,  is  permanent  until  another  change 
is  wrought  by  another  manifestation  of  chemical  action;  on  the  other 
hand,  the  peculiar  property  communicated  to  a  substance  by  a  physical 
force  is  temporary,  and  only  manifested  during  the  action  of  that  force. 

However  distinct  chemical  may  thus  be  from  physical  forces,  it  is 
none  the  less  united  with  them  in  that  grand  correlation  whose  existence 
was  first  announced  by  Grove,  in  1842.  As,  from  chemical  action,  mani- 
festations of  every  variety  of  physical  force  may  be  obtained:  light,  heat 
and  mechanical  force  from  the  oxidation  of  carbon;  and  electrical  force 
from  the  action  of  zinc  upon  sulphuric  acid — so  does  chemical  action  have 
its  origin,  in  many  instances,  in  the  physical  forces.  Luminous  rays  bring 
about  the  chemical  decomposition  of  the  salts  of  silver,  and  the  chemical 
union  of  chlorine  and  hydrogen;  by  electrical  action  a  decomposition  of 
many  compounds  into  their  constituents  is  instituted,  while  instances  are 
abundant  of  reactions,  combinations,  and  decompositions  which  require  a 
certain  elevation  of  temperature  for  their  production.  While,  therefor, 


2  GENERAL    MEDICAL    CHEMISTRY. 

chemistry  in  the  strictest  sense  of  the  term  deals  only  with  those  actions 
which  are  attended  by  a  change  of  composition  in  the  material  acted 
upon,  yet  chemical  actions  are  so  frequently,  nay  universally,  affected  by 
existing  physical  conditions,  that  the  chemist  is  obliged  to  give  his  at- 
tention to  the  science  of  physics,  in  so  far,  at  least,  as  it  has  a  bearing 
upon  chemical  reactions,  to  chemical  physics — a  branch  of  the  subject 
which  has  afforded  very  important  evidence  in  the  support  of  theoretical 
views  originating  from  purely  chemical  reactions. 


General  Properties  of  Matter. 

INDESTRUCTIBILITY. — The  result  of  chemical  action  is  change  in  the 
composition  of  the  substance  acted  upon,  a  change  accompanied  by  cor- 
responding alterations  in  its  properties.  Although  we  may  cause  matter 
to  assume  a  variety  of  different  forms  and  render  it,  for  the  time  being, 
invisible,  yet  in  none  of  these  changes  is  there  the  smallest  particle  of 
matter  destroyed.  Wfyen  carbon  is  burned  in  an  atmosphere  of  oxygen, 
it  disappears,  and,  so  far  as  we  can  learn  by  the  senses  of  sight  or  touch, 
is  lost;  but  the  result  of  the  burning  is  an  invisible  gas,  whose  weight  is 
equal  to  that  of  the  carbon  which  has  disappeared,  plus  the  weight  of  the 
oxygen  required  to  burn  it. 

WEIGHT. — All  bodies  attract  each  other  with  a  force  which  is  in  direct 
proportion  to  the  amount  of  matter  which  they  contain.  The  force  of 
this  attraction  exerted  upon  surrounding  bodies  by  the  earth  becomes 
sensible  as  weight,  when  the  motion  of  the  attracted  body  toward  the 
centre  of  gravity  of  the  earth  is  prevented. 

In  chemical  operations  we  have  to  deal  with   three  kinds  of  weight  : 
apparent,  absolute,  and  specific. 

The  apparent  weight,  or  relative  weight,  of  a  body  is  that  which  we 
usually  determine  with  our  balances,  and  is,  if  the  volume  of  the  body 
weighed  be  greater  than  that  of  the  counterpoising  weights,  less  than 
its  true  weight.  Every  substance  placed  in  a  liquid  or  gaseous  medium 
suffers  a  loss  of  apparent  weight  equal  to  that  of  the  volume  of  the  medium 
so  displaced,  and  is  buoyed  up  to  that  extent.  A  cork  placed  in  water 
sinks  until  it  has  displaced  a  volume  of  water  whose  weight  is  equal  to 
its  own.  For  this  reason  the  apparent  weight  of  some  substances  may  be 
a  minus  quantity;  thus,  if  the  air  contained  in  a  vessel  suspended  from  one 
arm  of  a  poised  balance  be  replaced  by  hydrogen,  that  arm  of  the  balance 
to  which  the  vessel  is  attached  will  rise,  indicating  a  diminution  in  weight. 

The  absolute  weight  of  a  body  is  its  weight  in  vacuo.  It  is  only  deter- 
mined in  very  accurate  chemical  work,  by  placing  the  entire  weighing  ap- 
paratus under  the  receiver  of  an  air-pump,  or,  in  the  case  of  gases,  ap- 
proximately, by  first  weighing  the  vessel  from  which  the  air  has  been 
pumped,  and  afterward  filled  with  the  gas. 

By  the  specific  weight,  or  specific  gravity  of  a  substance,  is  understood 
the  weight  of  a  given  volume  of  that  substance  as  compared  with  the 
weight  of  an  equal  volume  of  some  substance  taken  as  a  standard  of  com- 
parison. It  is  a  well-known  fact  that  equal  volumes  of  different  sub- 
stances differ  from  each  other  in  weight;  thus,  a  litre  of  hydrogen  weighs 


GENEBAL    PKOPEKTIES    OF    MATTER.  3 

0.0896  grams,  while  the  same  volume  of  platinum  weighs  21.500  grains, 
or  about  200,000  times  as  much. 

The  substance  taken  as  the  unit  of  the  specific  gravities  of  solids  and 
liquids  is  water.  The  specific  weights  of  gases  are  usually  referred  to  air 
as  a  unit;  it  is  better,  however,  to  adopt  hydrogen  as  such  unit  (see  p. 
15).  When  we  say  that  the  specific  gravity  of  sulphuric  acid  is  1.8,  we 
mean  that,  volume  for  volume,  sulphuric  acid  is  one  and  eight-tenths 
times  as  heavy  as  water. 

The  determination  of  the  specific  weight  of  a  substance  is  frequently 
of  great  service.  Sometimes  it  affords  a  rapid  means  of  distinguishing 
between  two  substances  similar  in  appearance ;  sometimes  in  determining 
the  quantity  of  an  ingredient  in  a  mixture  of  two  liquids,  as  alcohol  and 
water;  and  frequently  in  determining  approximately  the  quantity  of 
solid,  matter  in  solution  in  a  liquid;  it  is  the  last  object  which  we  have 
in  view  in  determining  the  specific  gravity  of  the  urine. 

An  aqueous  solution  of  a  solid  has  a  higher  specific  gravity  than  pure 
water,  the  increase  in  specific  gravity  following  a  regular  but  different 
rate  of  increase  with  each  solid.  In  a  simple  solution — one  of  common  salt 
in  water,  for  instance — the  proportion  of  solid  in  solution  can  be  deter- 
mined from  the  specific  gravity.  In  complex  solutions,  such  as  the  urine, 
the  specific  gravity  does  not  indicate  the  proportion  of  solid  in  solution 
with  accuracy.  In  the  absence  of  sugar  and  albumen,  a  determination  of 
the  specific  gravity  of  urine  affords  an  indication  of  the  amount  of  solids 
sufficiently  accurate  for  usual  clinical  purposes.  Moreover,  as  urea  is 
much  in  excess  over  other  urinary  solids,  the  oscillations  in  the  specific 
gravity  of  the  urine,  if  the  quantity  passed  in  twenty-four  hours  be  con- 
sidered, and  in  the  absence  of  albumen  and  sugar,  indicate  the  variations 
in  the  elimination  of  urea,  and  consequently  the  activity  of  disassimilation 
of  nitrogenous  material. 

To  determine  the  specific  gravity  of  substances,  different  methods  are 
adopted,  according  as  the  substance  is  in  the  solid,  liquid,  or  gaseous 
state  ;  is  in  mass  or  in  powder;  or  is  soluble  or  insoluble  in  water. 

Solids. — First.  The  substance  is  heavier  than  water,  insoluble  in  that 
liquid,  and  not  in  powder.  It  is  attached  by  a  fine  silk  fibre  to  a  hook 
suitably  situated  on  one  arm  of  the  balance,  and  weighed.  A  beaker  full 
of  pure  water  is  so  arranged  that  the  substance,  still  attached  to  the 
balance,  is  immersed  in  the  liquid;  in  which  condition  it  is  again  weighed. 
The  second  weight  will  be  found  to  be  less  than  the  first.  By  dividing 
the  weight  in  air  by  the  loss  in  water  the  specific  gravity,  water =1.00,  is 
obtained.  Example: 

A  piece  of  lead  weighs  in  air 82.0 

A  piece  of  lead  weighs  in  water 74.9 

Loss  in  water 7.1 

82.0 


7.1 


=  11.55  =  sp.  gr.  of  lead. 


If  the  substance  be  in  fine  powder,  the  specific  gravity  bottle  (see  p. 
4)  is  used.  The  bottle,  filled  with  water,  and  the  powder,  previously 
weighed  and  in  a  separate  vessel,  are  weighed  together.  The  water  is 


4  GENERAL    MEDICAL    CHEMISTRY. 

poured  out  of  the  bottle,  into  which  the  powder  is  then  introduced,  with 
enough  water  to  fill  the  bottle  completely.  The  weight  of  the  bottle  and 
its  contents  is  now  determined,  and  is  less  than  the  first  weight  by  the 
weight  of  the  volume  of  water  displaced  by  the  powder.  Here  again  the 
specific  gravity  is  obtained  by  dividing  the  weight  of  the  powder  alone 
by  the  loss  between  the  first  and  second  weighings. 

Second. — If  the  substance  be  lighter  than  water,  a  sufficient  bulk  of 
some  heavy  substance,  whose  specific  gravity  is  known,  is  attached  to  it 
and  the  same  method  followed,  the  loss  of  weight  of  the  heavy  substance 
being  subtracted  from  the  total  loss.  Example:  '' 

A  fragment  of  wood  weighs 24 

A  fragment  of  lead  weighs 44 

Wood  with  lead  attached  weighs 68 

Wood  with  lead  attached  weighs  in  water. ...    16 

Loss  of  weight  of  combination 52 

Loss  of  weight  of  lead  in  water 6 

Loss  of  weight  cf  wood 46 

24 

—  =  0.5217 =sp.  gr.  of  wood. 

46 

Third. — If  the  substance  be  soluble  in  water,  its  specific  gravity,  re- 
ferred to  some  liquid  in  which  it  is  insoluble  and  whose  specific  gravity  is 
known,  is  determined  by  using  that  liquid  as  water  is  used  in  1°.  From 
this  the  specific  gravity  of  the  solid,  referred  to  water,  is  determined  by 
multiplying  the  specific  gravity  so  obtained  by  that  of  the  liquid  used. 
Example : 

A  piece  of  potassium  weighs 2.576 

A  specific  gravity  bottle  full  of  naphtha,  sp.  gr.  0.758, 

weighs 22.784 

25.360 
The  bottle  with  potassium  and  naphtha  weighs 23.103 


Loss 2.257 

2.576 


2.257 


—  1.141  x0.75S=0.865=Sp.  gr..  of  potassium. 


Liquids. — The  specific  gravity  of  liquids  is  determined  by  the  specific 
gravity  bottle,  sometimes  called  picnometer,  or  by  the  spindle  or  hydrom- 
eter. 

First. — The  method  by  the  bottle  is  the  more  accurate,  and,  if  a  bal- 
ance be  at  hand,  easily  conducted.  A  bottle  of  thin  glass  is  so  made  as 
to  contain  exactly  a  given  volume  of  distilled  water  at  a  given  tempera- 
ture, say  100  c.c.  at  15°  C.  ;  the  weight  of  the  bottle  is  also  known  once 
for  all.  To  use  the  picnometer,  it  is  simply  filled  with  the  liquid  to  be  ex- 


GENERAL    PROPERTIES    OP    MATTER.  5 

amined  and  weighed.  The  weight  obtained,  minus  that  of  the  bottle,  is  the 
specific  gravity  sought  if  the  bottle  contain  1000  c.c.;  y1^  if  100  c.c.,  etc. 
Example:  having  a  bottle  whose  weight  is  35.35,  and  which  contains  100 
c.c. ;  filled  with  urine  it  weighs  137.91,  the  specific  gravity  of  the  urine  is 
137.91—35.35  =  102.56x10=1025.6 Water =1000. 

Second.- — The  method  by  the  hydrometer  is  based  upon  the  fact  that 
a  solid  will  sink  in  a  liquid  until  it  has  displaced  a  volume  of  the  liquid 
whose  weight  is  equal  to  its  own;  and  all  forms  of  hydrometers  are  sim- 
ply contrivances  to  measure  the  volume  of  liquid  which  they  displace  when 
immersed.  The  appearance  of  the  hydrometer  most  used  by  physicians, 
the  urinometer,  is  too  well  known  to  require  description.  It  should 
not  be  chosen  too  small,  as  the  larger  the  bulb  and  the  thinner  and  longer 
the  stem,  the  more  accurate  will  be  its  indications.  Owing  to  prevailing 
carelessness  in  the  manufacture  of  urinometers  and  to  the  impossibility  of 
reading  the  graduations  with  the  same  accuracy  that  can  be  attained  in 
detecting  small  differences  in  weight,  their  indications  are  never  as  pre- 
cise as  those  obtained  by  the  picnometer. 

In  all  determinations  of  specific  gravity  it  is  of  great  importance  to 
have  the  liquid  examined  at  the  temperature  for  which  the  instrument  is 
graduated,  for  the  reason  that  all  liquids  expand  with  heat  and  contract 
•when  cooled,  and  consequently  the  result  obtained  will  be  too  low  if  the 
urine  or  other  liquid  be  at  a  temperature  above  that  at  which  the  instru- 
ment is  intended  to  be  used,  and  too  high  if  below  that  temperature.  An 
accurate  correction  may  be  made  for  temperature  in  simple  solutions;  in 
a  complex  fluid  like  the  urine,  however,  this  can  only  be  done  roughly  by 
allowing  1°  of  specific  gravity  for  each  3°  C.  (5.4°  Fahr.)  of  variation  in 
temperature. 

The  determination  of  the  specific  gravity  of  gases  and  vapors  requires 
all  the  facilities  of  a  well-appointed  laboratory,  and,  although  of  the 
greatest  importance  to  the  chemist  (see  p.  15),  will  rarely  be  attempted 
by  the  physician. 

STATES  OF  MATTER. — Matter  exists  in  one  of  three  states,  solid,  liquid, 
and  gaseous.  In  the  solid  form  the  particles  of  matter  are  comparatively 
close  together,  and  are  separated  with  more  difficulty  than  are  those  of 
liquid  or  gaseous  matter;  or,  in  other  words,  the  cohesion  of  solid  matter 
is  greater  than  that  of  the  other  two  forms.  In  the  liquid  the  particles 
are  less  firmly  bound  together  and  are  capable  of  freer  motion  about  one 
another.  In  the  gas  the  mutual  attraction  of  the  particles  disappears 
entirely,  and  their  distance  from  each  other  depends  upon  the  pressure  to 
which  the  gas  is  subjected. 

The  term  fluid  applies  to  both  liquids  and  gases,  the  former  being 
designated  as  incompressible,  from  the  very  slight  degree  to  which  their 
volume  can  be  reduced  by  pressure.  The  gases  are  designated  as  com- 
pressible fluids,  from  the  fact  that  their  volume  can  be  reduced  by  pres- 
sure to  an  extent  limited  only  by  their  passage  into  the  liquid  form. 

It  is  highly  probable  that  all  substances  which  are  not  decomposed 
when  heated  are  capable  of  existing  in  the  three  forms  of  solid,  liquid, 
and  gas.  There  are,  however,  some  substances  which  are  only  known  in 
two  forms — as  alcohol,  or  in  a  single  form — as  carbon;  probably  because  we 
are  as  yet  unable  to  produce  artificially  a  temperature  sufficiently  low  to 
solidify  the  one,  or  sufficiently  high  to  liquefy  or  volatilize  the  other. 

The  passage  of  a  substance  from  one  form  to  another  is  always  at- 
tended by  the  absorption  or  liberation  of  a  definite  amount  of  heat.  In 
passing  from  the  solid  to  the  gaseous  form  a  body  absorbs  a  definite 


6  GENERAL    MEDICAL    CHEMISTRY. 

amount  of  heat  with  each  change  of  form.  If  a  given  quantity  of  ice  at 
a  temperature  below  the  freezing-point  of  water  be  heated,  its  tempera- 
ture gradually  rises  until  the  thermometer  marks  0°  C.,  at  which  point 
it  remains  stationary  until  the  last  particle  of  ice  has  disappeared.  At 
that  time  another  rise  of  the  thermometer  begins,  and  continues  until 
100°  C.  is  reached  (at  760  mm.  of  barometric  pressure),  when  the  water 
boils,  and  the  thermometer  remains  stationary  until  the  last  particle  of 
water  has  been  converted  into  steam;  after  which,  if  the  application  of 
heat  be  continued,  the  thermometer  again  rises.  During  these  two  periods 
of  stationary  thermometer,  heat  is  taken  up  by  the  substance,  but  is  not 
indicated  by  the  thermometer  or  by  the  sense.  Not  being  sensible,  it  is 
said  to  be  latent,  a  term  which  is  liable  to  mislead,  as  conveying  the  idea 
that  heat  is  stored  up  in  the  substance  as  heat;  such  is  not  the  case. 
During  the  period  of  stationary  thermometer  the  heat  is  not  sensible  as 
heat,  for  the  reason  that  it  is  being  used  up  in  the  work  required  to  effect 
that  separation  of  the  particles  of  matter  which  constitutes  its  passage 
from  solid  to  liquid  or  from  liquid  to  gas.  The  amount  of  heat  required 
to  bring  about  the  passage  of  a  given  weight  of  a  substance  from  the 
denser  to  the  rarer  form  is  always  the  same,  and  the  temperature  indicated 
by  the  thermometer  during  this  passage  is  always  the  same  for  that  sub- 
stance, unless  in  either  case  a  modification  be  caused  by  a  variation  in 
pressure.  The  degree  of  temperature  indicated  by  the  thermometer  while 
a  substance  is  passing  from  the  solid  to  the  liquid  state  is  called  iisfusing- 
point'  that  indicated  during  its  passage  from  the  liquid  to  the  gaseous 
form,  its  boiling^oint. 

The  absorption  of  heat  by  a  volatilizing  liquid  is  utilized  in  the  arts 
and  in  medicine  for  the  production  of  cold  (which  is  simply  the  absence  of 
heat),  in  the  manufacture  of  artificial  ice  and  in  the  production  of  local 
anaesthesia  by  the  ether-spray.  The  removal  of  heat  from  the  body  in  this 
way,  by  the  evaporation  of  perspiration  from  the  surface,  is  an  important 
factor  in  the  maintenance  of  the  body  temperature  at  a  point  consistent 
with  life. 

When  a  substance  passes  from  a  rarer  to  a  denser  form  it  gives  out — 
liberates — an  amount  of  heat  equal  to  that  which  it  absorbed  in  its  pas- 
sage in  the  opposite  direction.  It  is  for  this  reason  that,  while  we  apply 
heat  to  convert  a  liquid  into  a  vapor,  we  apply  cold  to  reduce  a  gas  to  a 
liquid.  As  a  rule,  the  thermometrical  indication  is  the  same  in  which- 
ever direction  the  change  of  form  occurs;  some  substances,  however,  so- 
lidify at  a  temperature  slightly  different  from  that  at  which  they  fuse. 

Most  solids,  when  heated,  are  first  converted  into  liquids,  and  these 
into  gases;  there  are,  however,  some  exceptions  to  this  rule.  Solids  which 
pass  directly  from  the  solid  to  the  gaseous  form  are  said  to  sublime. 

DIVISIBILITY. — All  substances  are  capable  of  being  separated,  with 
greater  or  less  facility,  by  mechanical  means  into  minute  particles.  With 
suitable  apparatus,  gold  may  be  divided  into  fragments,  visible  by  the  aid 
of  the  microscope,  whose  weight  would  be  g  o  o  o  o  0*0  o  o  o  o  o  °^  a  grain;  and 
it  is  probable  that  when  a  solid  is  dissolved  in  a  liquid  a  still  greater  sub- 
division is  attained. 

Although  we  have  no  direct  experimental  evidence  of  the  existence  of 
a  limit  to  this  divisibility,  we  are  warranted  in  believing  that  matter  is  not 
infinitely  divisible.  A  strong  argument  in  favor  of  this  view  being  that, 
after  physical  subdivision  has  reached  the  limit  of  its  power  with  regard  to 
compound  substances,  these  may  be  further  divided  into  dissimilar  bodies 
by  chemical  means. 


LAWS    GOVERNING    THE    COMBINATION    OF    ELEMENTS.  7 

The  limit  of  mechanical  subdivision  is  the  molecule  of  the  physicist, 
the  smallest  quantity  of  matter  with  which  he  has  to  deal. 


Elements  and  Compounds. 

If  we  examine  the  various  substances  existing  upon  and  in  our  earth, 
we  find  that  many  of  them  can  be  so  decomposed  as  to  yield  two  or  more 
other  substances,  distinct  in  their  properties  from  the  substance  from 
whose  decomposition  they  resulted,  and  from  each  other.  If,  for  ex- 
ample, sugar  be  treated  with  sulphuric  acid  it  blackens,  and  after  a 
while  a  mass  of  charcoal  separates.  Upon  further  examination  we  find 
that  water  has  also  been  produced.  From  this  water  we  may  by  simple 
means  obtain  two  gases,  differing  from  each  other  widely  in  their  proper- 
ties. Sugar  is  therefor  made  up  of  carbon  and  the  two  gases,  hydrogen 
and  oxygen;  but  it  has  the  properties  of  sugar,  and  not  those  of  either  of 
its  constituent  parts.  Moreover,  if  we  analyze  any  number  of  samples  of 
pure  sugar,  we  will  find  all  of  them  to  contain  the  same  proportionate 
quantities  of  carbon,  hydrogen,  and  oxygen  (see  below).  Such  a  substance 
as  sugar  is  called  a  compound. 

There  exist  in  nature  other  substances  which  it  has  been  impossible, 
hitherto,  to  decompose  into  other  dissimilar  bodies;  such  as  those  are 
called  simple  substances  or  elements. 

There  are  sixty-four  elements  at  present  known;  but  it  is  probable 
that,  as  our  methods  of  investigation  are  improved,  this  number  will  be  in- 
creased by  the  discovery  of  other  elements,  existing  only  in  small  quanti- 
ties. Indeed,  during  the  past  year  or  two  the  discovery  of  elements  not 
included  in  the  above  number,  scandium,  decipium,  philippium,  and  of 
ytterbium,  has  been  announced. 


Laws  Governing  the  Combination  of  Elements. 

The  alchemists,  Arabian  and  European,  contented  themselves  in  accu- 
mulating a  store  of  knowledge  of  isolated  phenomena,  without,  as  far  as  we 
know,  attempting,  in  any  serious  way,  to  group  them  in  such  a  manner  as 
to  learn  the  laws  governing  their  occurrence.  It  was  not  until  the  latter 
part  of  the  last  century,  1777,  that  Wenzel,  of  Dresden,  implied,  if  he  did 
not  distinctly  enunciate,  what  is  known  as  the  law  of  reciprocal  propor- 
tions. A  few  years  later,  Richter,  of  Berlin,  confirming  the  work  of 
Wenzel,  added  to  it  the  law  of  definite  proportions,  usually  called  Dai- 
ton's  first  law.  Finally,  as  the  result  of  his  investigations  from  1804  to 
1808,  Dalton  added  the  law  of  multiple  proportions,  and,  reviewing  the 
work  of  his  predecessors,  enunciated  the  results  clearly  and  distinctly. 

Considering  these  laws,  not  in  the  order  of  their  discovery,  but  in  that 
of  their  natural  sequence,  we  have: 

The  law  of  definite  proportions,  stated  in  modern  language,  is  that 
the  relative  weights  of  elementary  substances  in  a  compound  are  definite 
and  invariable.  If,  for  example,  we  analyze  water,  we  find  that  it  is  com- 
posed of  eight  parts  by  weight  of  oxygen  for  each  part  by  weight  of  hydro- 
gen, and  that  this  proportion  exists  in  every  instance,  whatever  the  source 
of  the  water.  If,  instead  of  decomposing,  or  analyzing  water,  we  start 
from  its  elements,  and,  by  synthesis,  cause  them  to  unite  to  form  water,  we 
find  that,  if  the  mixture  be  made  in  the  proportion  of  eight  oxygen  to 


8  GENERAL   MEDICAL    CHEMISTRY. 

one  hydrogen  by  weight,  the  entire  quantity  of  each  gas  will  be  consumed 
in  the  formation  of  water.  But  if  an  excess  of  either  have  been  added  to 
the  mixture,  that  excess  will  remain  after  the  combination.  This  is 
true  of  all  chemical  compounds,  and  in  this  we  have  one  distinction  be- 
tween a  chemical  compound  and  a  mere  mixture  of  two  substances;  in 
the  former  the  proportion  of  the  constituents  is  always  the  same,  while 
in  the  latter  it  is  variable.  Another  distinction  between  compounds  and 
mixtures  is  that  the  former  have  properties  distinct  from  those  of  their 
constituents,  and  that  the  properties  of  these  only  become  evident  after 
decomposition  of  the  compound;  while  mixtures  possess  the  properties 
inherent  in  one  or  all  of  their  constituents. 

The  law  of  multiple  proportions,  or  Dalton's  second  law,  is  that  when 
two  elements  unite  with  each  other  to  form  more  than  one  compound,  the 
resulting  compounds  contain  simple  multiple  proportions  of  one  element 
as  compared  with  a  constant  quantity  of  the  other. 

Oxygen  and  nitrogen,  for  example,  unite  with  each  other  to  form  no 
less  than  five  compounds.  Upon  analysis  we  find  that  in  these  the  two 
elements  bear  to  each  other  the  following  relations  by  weight: 

In  the  first,        14  parts  of  nitrogen  to  8  of  oxygen. 
In  the  second,  14  parts  of  nitrogen  to  8  x  2  =  16  of  oxygen. 
In  the  third,      14  parts  of  nitrogen  to  8  x  3=24  of  oxygen. 
In  the  fourth,   14  parts  of  nitrogen  to  8  X  4=32  of  oxygen. 
In  the  fifth,       14  parts  of  nitrogen  to  8  x  5=40  of  oxygen. 

Finally,  the  third  law,  that  of  reciprocal  proportions,  is  to  the  effect 
that  the  ponderable  quantities  in  which  substances  unite  with  the  same 
substance  express  the  relation,  or  a  simple  multiple  thereof,  in  which  they 
unite  loith  each  other.  Or,  as  Wenzel  stated  it,  "  the  weights  b,  b',  b"  of 
several  bases  which  neutralize  the  same  weight  a  of  an  acid  are  the  same 
which  will  neutralize  a  constant  weight  a'  of  another  acid ;  and  the  weights 
a,  a,'  a,"  of  different  acids  which  neutralize  the  same  weight  b  of  a  base 
are  the  same  which  will  neutralize  a  constant  weight  of  another  base  Z»'." 


The  Atomic  Theory. 

The  laws  of  Wenzel,  Richter,  and  Dalton,  given  above,  are  simply  gen- 
eralized statements  of  certain  groups  of  facts,  and,  as  such,  not  only  admit 
of  no  doubt,  but  are  the  foundations  upon  which  chemistry  as  an  exact 
science  is  based.  Dalton,  seeking  an  explanation  of  the  reason  of  being 
of  these  facts,  was  led  to  adopt  the  view,  held  by  the  Greek  philosopher 
Democritus,  that  matter  was  not  infinitely  divisible.  He  retained  the 
name  atom  (arop;s= indivisible),  given  by  Democritus  to  the  ultimate 
particles  of  which  matter  was  supposed  by  him  to  be  composed;  but  ren- 
dered the  idea  more  precise  by  ascribing  to  these  atoms  real  magnitude 
and  a  definite  weight,  and  by  considering  elementary  substances  as  made 
up  of  atoms  of  the  same  kind,  and  compounds  as  consisting  of  atoms  of 
different  kinds. 

This  hypothesis,  the  first  step  toward  the  atomic  theory  as  entertained 
to-day,  afforded  a  clear  explanation  of  the  numerical  results  stated  in  the 
three  laws.  If  hydrogen  and  oxygen  always  unite  together  in  the  propor- 
tion of  one  of  the  former  to  eight  of  the  latter,  it  is  because,  said  Dalton, 
the  compound  consists  of  an  atom  of  hydrogen,  weighing  1,  and  an  atom 


THE    ATOMIC    THEORY.  9 

of  oxygen,  weighing  8.     If,  again,  in  the  compounds    of  nitrogen    and 

oxygen,  we  have  the  two  elements  uniting  in  the  proportions  14  :  8 • 

14:  8  x  2 14  :  8  x  3 14  :  8  x  4 14  :  8  x  5,  it  is  because  they  are 

severally  composed  of  an  atom  of  nitrogen  weighing  14,  united  to  1,  2, 
3,  4  or  5  atoms  of  oxygen,  each  weighing  8.  Further,  that  compounds  do 
not  exist  in  which  any  fraction  of  8  oxygen  enters,  because  8  is  the 
weight  of  the  indivisible  atom  of  oxygen. 

One  of  the  chief  advantages  of  Dalton's  hypothesis  is  in  the  intro- 
duction of  this  precise  and  simple  relation  between  the  quantities  of  the 
constituents  of  a  compound.  Chemists  before  Dalton's  day,  in  express- 
ing the  results  of  their  analyses,  did  not  progress  beyond  statements  of 
the  percentage  composition.  Expressing  the  composition  of  four  of  the 
carbon  compounds  in  percentages,  we  have: 

Carbon.       Hydrogen.        Oxygen. . 

Marsh  gas 75.0  25.0  ....  =100 

Olefiantgas 85.7  14.3  =100 

Carbonic  oxide 42.9  57.1  =100 

Carbonic  acid 27.3  ....  72.7  =100 

At  first  sight,  these  figures  convey  nothing  beyond  the  mere  centesimal 
composition  of  the  substances  which  they  express.  The  cardinal  point 
of  Dalton's  discovery  lies  in  his  translation  of  them  into  the  simple  rela- 
tions: 

Carbon.  Hydrogen.       Oxygen. 

Marsh  gas 6  2 

Olefiant  gas 6  1 

Carbonic  oxide 6  . .  8 

Carbonic  acid 6  . .  16 

Dalton's  hypothesis  of  the  existence  of  atoms  as  definite  quantities  did 
not,  however,  meet  with  general  acceptance.  Davy,  Wollaston,  and  others 
considered  the  quantities  in  which  Dalton  had  found  the  elements  to  unite 
with  each  other,  as  mere  proportional  numbers,  or  equivalents,  as  they 
expressed  it,  nor  is  it  probable  that  Dalton's  views  would  have  received 
any  further  recognition  until  such  time  as  they  might  have  been  exhumed 
from  some  musty  tome,  had  their  publication  not  been  closely  followed 
by  that  of  the  results  of  the  labors  of  Humboldt  and  of  Gay  Lussac,  con- 
cerning the  volumes  in  which  gases  unite  with  each  other. 

In  the  form  of  what  are  known  as  Gay  Lussac's  laws,  these  results  are: 

First. — TJiere  exists  a  simple  relation  between  the  volumes  of  gases 
which  combine  with  each  other. 

Second. — Tfiere  exists  a  simple  relation  between  the  sum  of  the  volumes 
of  the  constituent  gases y  and  the  volume  of  the  gas  formed  by  their  union. 
For  example: 


1  volume   chlorine  unites  with   1   volume  hydrogen  to  form   2   volumes 

hydrochloric  acid. 
1  volume    oxygen   unites  with   2  volumes    hydrogen   to  form  2  volumes 

vapor  of  water. 
1  volume  nitrogen  unites  with  3  volumes  hydrogen  to  form  2  volumes 

ammonia. 


10  GENERAL    MEDICAL    CHEMISTRY. 

1  volume  oxygen    unites  with  1  volume    nitrogen    to    form  2   volumes 

nitric  oxide. 
1   volume  oxygen   unites  with   2  volumes    nitrogen   to   form  2   volumes 

nitrous  oxide. 

' "  •  . 

Berzelius,  basing  his  views  upon  these  results  of  Gay  Lussac,  modified 
the  hypothesis  of  Dalton  and  established  a  distinction  between  the  equi- 
valents and  atoms.  The  composition  of  water  he  expressed,  in  tte  nota- 
tion which  he  was  then  introducing,  as  being  H2O,  and  not  HO  as  Dai- 
ton's  hypothesis  called  for.  As,  however,  Berzelius  still  considered  the 
atom  of  oxygen  as  weighing  8,  he  was  obliged  also  to  consider  the  atoms 
of  hydrogen  and  of  certain  other  elements  as  double  atoms — a  fatal  defect 
in  his  system,  which  led  to  its  overthrow  and  the  re-establishment  of  the 
formula  HO  for  water. 

It  was  reserved  to  Gerhardt  to  clearly  establish  the  distinction  be- 
tween atom  and  molecule;  to  observe  the  bearing  of  the  discoveries  of 
Avogadro  and  Ampere  upon  chemical  philosophy;  and  thus  to  establish 
the  atomic  theory  as  entertained  at  present. 

As  a  result  of  his  investigations  in  the  domain  of  organic  chemistry, 
Gerhardt  found  that,  if  Dalton's  equivalents  be  adhered  to,  whenever 
carbonic  acid  or  water  is  liberated  by  the  decomposition  of  an  organic 
substance,  it  is  invariably  in  double  equivalents,  never  in  single  ones; 
always  2CO2  or  2HO  or  some  multiple  thereof,  never  CO2  or  HO.  He 
further  found  that  if  the  equivalents  C=6,  H  =  l,  andO  =  8be  retained,  the 
formulae  became  such  that  the  equivalents  of  carbon  are  always  divisible 
by  two.  In  fact,  he  found  the  same  objections  to  apply  to  the  notation 
then  in  use,  that  had  been  urged  against  that  of  Berzelius. 

In  1811,  Avogadro,  from  purely  physical  researches,  had  been  enabled  to 
state  the  law  which  is  now  known  by  his  name,  to  the  effect  that  equal 
volumes  of  all  gases,  under  like  conditions  of  temperature  and  pressure, 
contain  equal  numbers  of  molecules. 

In  the  hands  of  Gerhardt  this  law,  in  connection  with  those  of  Gay 
Lussac,  became  the  foundation  of  what  is  sometimes  called  the  "  new 
chemistry."  Bearing  in  mind  Avogadro's  law,  we  may  translate  the  first 
three  combinations  given  in  the  table  on  p.  9  into  the  following: 

1  molecule   of   chlorine  unites  with  1  molecule  of  hydrogen  to  form  2 

molecules  of  hydrochloric  acid. 
1  molecule  of  oxygen  unites  with   2  molecules  of  hydrogen  to  form  2 

molecules  of  vapor  of  water. 
1  molecule  of  nitrogen  unites  with   3  molecules  of  hydrogen  to  form  2 

molecules  of  ammonia. 

But  the  ponderable  quantities  in  which  these  combinations  take  place 
are: 

35.5  chlorine  to 1  hydrogen. 

16  oxygen  to 2  hydrogen. 

14  nitrogen  to 3  hvdrogen. 

And  as  single  molecules  of  hydrogen,  oxygen,  and  nitrogen  are  in  these 
combinations  subdivided  to  form  2  molecules  of  hydrochloric  acid,  water, 
and  ammonia,  it  follows  that  these  molecules  must  each  contain  two 
equal  quantities  of  hydrogen,  oxygen,  and  nitrogen,  less  in  size  than  the 
molecules  themselves.  And,  further,  as  in  these  instances  each  molecule 


ATOMIC    AND   MOLECULAR    WEIGHTS VALENCE.  11 

contains  two  of  these  smaller  quantities,  or  atoms,  the  relation  between 
the  weights  of  the  molecules  must  be  also  the  relation  between  the 
weights  of 'the  atoms,  and  we  may  therefor  express  the  combinations 
thus: 

1  atom  of  chlorine  weighing          .,          .  ,  j  1  atom  of  hydrogen  weighing 
35.5  (        1; 


1  atom  of  oxygen  weighing 

16 
1  atom  of  nitrogen  weighing 

14 


unites  with  \  2  atoms  °f  Mrogen  weighing 

(         1  each; 
unites  with  \  3  atoms  of  hydrogen  weighing 

(        1  each; 


and  consequently,  if  the  atom  of  hydrogen   weighs   1,  that  of  chlorine 
weighs  35.5,  that  of  oxygen  16,  and  that  of  nitrogen  14.' 


Atomic  and  Molecular  Weights — Valence. 

Atomic  weights. — The  distinction  between  molecules  and  atoms  may 
be  expressed  by  the  following  definitions: 

A.  molecule  is  the  smallest  quantity  of  any  substance  that  can  exist  in 
the  free  state. 

An  atom  is  the  smallest  quantity  of  an  elementary  substance  that  can 
enter  into  a  chemical  reaction. 

The  molecule  is  always  made  up  of  atoms,  upon  whose  nature,  num- 
ber, and  arrangement  with  regard  to  each  other,  the  properties  of  the  sub- 
stance depend.  In  an  elementary  substance  the  atoms  composing  the 
molecules  are  the  same  in  kind,  and  usually  two  in  number.  In  com- 
pound substances  they  are  dissimilar  and  vary  in  quantity  from  two  in  a 
simple  compound,  like  hydrochloric  acid,  to  several  hundreds  in  the  more 
complex  organic  substances.  Obviously,  the  word  atom  can  only  be  used 
in  speaking  of  an  elementary  body,  and  that  only  while  it  is  passing 
through  a  reaction.  The  term  molecule,  on  the  other  hand,  applies  indif- 
ferently to  elements  and  compounds. 

The  atoms  have,  as  we  have  seen,  definite  relative  weights;  and  upon 
an  exact  determination  of  these  weights  depends  the  entire  science  of 
quantitative  analytical  chemistry.  A  vast  amount  of  labor  has  been  be- 
stowed upon  fixing  these  quantities  accurately.  Berzelius,  who  was  the 
first  to  recognize  their  importance,  devoted  over  thirty  years  to  the  task, 
which  he  performed  so  carefully  that  many  of  the  weights  which  he  gave 
are  those  still  in  use.  Subsequently,  as  new  elements  were  discovered, 
and  as  methods  of  investigation  were  improved,  other  determinations 
were  made  by  Dumas,  Marignac,  Erdmann,  Marchand,  Stas,  Cooke,  and 
others. 

These  weights,  determined  by  repeated  and  careful  analyses  of  per- 
fectly pure  compounds  of  the  elements,  express  the  weight  of  one  atom 
of  the  element  as  compared  with  the  weight  of  one  atom  of  hydrogen, 
that  being  the  lightest  element  known.  What  the  absolute  weight  of  an 
atom  of  any  element  may  be  we  do  not  know,  nor  would  the  knowledge 
be  of  any  service  did  we  possess  it. 

The  following  table  contains  a  list  of  the  elements  at  present  known, 
with  their  atomic  weights: 


12 


GENERAL    MEDICAL    CHEMISTRY. 


ELEMENTS. 


NAME. 

Symbol. 

B. 

-  Atomic 
weight. 

C. 

Specific  heat. 

D. 

Atomic 
heat. 
BxC. 

Aluminium  .  .         

Al. 

27.5 

0,2143 

5.89 

Antimony  

Sb. 

120 

0.05077 

6.09 

Arsenic  

As. 

75 

0.08140 

6.10 

Barium  

Ba. 

137.2 

Bismuth  

Bi. 

210 

0.03084 

6.48 

Boron  

Bo. 

11 

0.3663 

3.99 

Bromine   

Br. 

79.952 

0.08432 

6.74 

Cadmium  

Cd. 

112 

0.05669 

-  6.35 

Caesium  

Cs. 

132.6 

Calcium  ... 

Ca. 

40 

0.17 

6.80 

Carbon  

C. 

12 

0.4589 

5.51 

Cerium  .  . 

Ce. 

138 

0  04479 

6  18 

Chlorine  

Cl. 

35.457 

0.093 

3.30 

Chromium  

Cr. 

52.4 

Cobalt  

Co. 

59 

0  10696 

6  31 

Copper  .  . 

Cu. 

63.5 

0.09515 

6.04 

Didymium 

D. 

144.78 

0.04563 

6.60 

Erbium   

E. 

162 

Fluorine  

Fl. 

19 

Gallium  

Ga. 

69.9 

0.0802 

5.61 

Glucinum  

Gl. 

13.8 

0.4079 

5.63 

Gold  

Au. 

197 

0.03244 

6.39 

Hydrogen  . 

H. 

1 

2.41 

2.41 

T      J'         & 

Indium   

In. 

113.4 

0.057 

6.46 

Iodine  

I. 

126.85 

0.05412 

6.87 

Iridium  

Ir. 

197.2 

0.03259 

6.43 

Iron  

Fe. 

56 

0  11379 

6.37 

Lanthanium  

La. 

139 

0  .  04485 

6.23 

Lead  

Pb. 

206.92 

0.03140 

6.50 

Lithium  .... 

Li. 

7 

0.9408 

6.58 

Magnesium  

Mg. 

24 

0.2499 

6.00 

Manganese  

Mn. 

55.2 

0  1217 

6.72 

Mercury  

Ho-. 

200 

0  03332 

6  66 

Molybdenum  

» 
Mo. 

96 

0  07218 

6.93 

Nickel  

Ni 

59 

0  10863 

6  41 

Niobium  

Nb 

94 

Nitrogen  .... 

N. 

14  044 

0  1652 

2.32 

Osmium  

Os 

200 

0  03113 

6  23 

Oxygen  

o 

16 

0  145 

2.32 

Palladium  

Pd. 

106  5 

0  0593 

6.32 

Phosphorus  

P 

31 

0.1887 

5  85 

Platinum  

Pt 

198 

0  03244 

6.42 

Potassium  

K 

39  137 

0  1655 

6  48 

Rhodium  

Rh 

104 

0  05803 

6  04 

Rubidium  

Rb 

85  4 

Ruthenium  .'.  . 

Ru. 

104 

ATOMIC    AND    MOLECULAR    WEIGHTS VALENCE. 


13 


ELEMENTS—  Continued. 


NAME. 

A. 

Symbol. 

B. 

Atomic 
weight. 

c. 

Specific  heat. 

D. 

Atomic 
heat. 
BxC. 

Selenium  

Se. 

79 

0.08468 

6.69 

Si. 

28 

0.2029 

5.68 

Silver  

Ag. 

107.93 

0.05701 

6.15 

Sodium  

N!. 

23.043 

0.2934 

6.76 

Strontium  

Sr. 

87.5 

Sulphur  

S. 

32.075 

0.20259 

6.50 

Tantalum   ... 

Ta. 

137.6 

Tellurium.           

Te. 

128 

0.05155 

6.59 

Thallium     

Tl. 

204 

0.03355 

6.84 

Thorium  

Th. 

234 

Tin  

Sn. 

118 

0.05623 

6.63 

Titanium  

Ti. 

50 

Tungsten  

W. 

184 

0.03342 

6.15 

Uranium         .        ... 

u. 

120 

V. 

51  3 

Yttrium  

Y. 

92.5 

Zn. 

65.2 

0.09555 

6.23 

Zirconium  

Zr. 

£9.6 

0.0666 

5.97 

We  are  not  limited  to  chemical  means  in  fixing  atomic  weights;  in- 
deed, cases  frequently  arise  in  which  the  results  of  numerous  analyses  are 
such  as  would  agree  with  one  or  more  numbers  equally  well.  In  these 
cases  we  obtain  valuable  indications  from  the  physical  properties  of  the 
substances  whose  atomic  weights  are  not  clearly  definable  by  chemical 
means. 

A  most  valuable  aid  in  this  respect  is  the  law  of  Dulong  and  Petit. 
These  observers  found,  in  1819,  that  there  existed  a  definite  relation  be- 
tween the  atomic  weight  of  an  element  and  its  specific  heat  (see  p.  30), 
and  that  the  product  obtained  by  multiplying  these  two  quantities  to- 
gether was,  with  a  few  exceptions,  nearly  constant.  While  the  atomic 
weights'  differ  greatly  from  each  other — 7  and  234  being  the  extremes — 
the  specific  heats  differ  in  an  opposite  manner,  and  to  such  an  extent 
that  the  product  obtained  by  multiplying  the  two  together  does  not 
vary  much  from  6.4.  This  product  is  given  for  each  element  in  the 
above  table  as  its  atomic  heat. 

If  by  analytical  means  we  are  unable  to  determine  which  of  two 
numbers  is  the  correct  atomic  weight  of  an  element,  we  determine  its 
specific  heat  and  select  that  one  of  the  two  numbers  under  consideration 
which,  when  multiplied  by  the  specific  heat,  gives  a  result  most  nearly 
approaching  6.4. 

It  will  be  noticed,  on  examining  the  table,  that  the  atomic  heats  of 
certain  of  the  elements  vary  considerably  from  the  rule.  The  atomic 
heats  of  carbon,  boron,  silicon,  sulphur,  and  phosphorus  are  subject  to- 
great  variations,  as  will  be  seen  in  the  following  table  : 


14  GENERAL    MEDICAL    CHEMISTRY. 

Specific  Atomic 

heat.  heat. 

BORON. 

Crystallized        at-  39.6° 0.1915  2.11 

Crystallized        at+   76.7° 0.2737  3.01 

Crystallized        at +233.2° . . . 0.3663  3.99 

Amorphous 0.255  2.81 

CARBON. 

Diamond             at—  50.5° 0.0635  0.76 

Diamond             at+140°    0.2218  2.66 

Diamond             at +985°    0.4589  5.51 

Graphite             at-  50.3° 0.1138  1.37 

Graphite             at+138.5° 0.2542  3.05 

Graphite              at+977.9° 0.4670  5.60 

Wood  charcoal 0.2415  '  2.90 

SILICON. 

Crystallized         at  -  39.8° 0.1360  3.81 

Crystallized         at+128.7° 0.1964  5.50 

Crystallized         at-f  232.4° 0.2029  5.68 

Fused  at  +  100°    0.175  4.90 

SULPHUR. 

Orthorhombic     at+   45°  0.163  5.22 

Orthorhombic     at+   99°  0.1776  5.68 

Liquid  at +  150°  0.234  7.49 

Recently  fused  at+   98°  0.20259  6.48 

PHOSPHORUS. 

Yellow  at-  78°  0.174  5.39 

Yellow  at  +  36°  0.202  6.26 

Liquid  at +100°  0.212  6.57 

Amorphous  at+   98°  0.170  5.27 

It  will  be  observed  that,  as  the  temperature  of  the  solid  element  is 
increased,  the  atomic  heat  more  nearly  approaches  6.4.  It  will  further 
be  noticed  that  those  elements  with  which  the  perturbations  occur  are 
precisely  those  which  are  capable  of  existing  in  two  or  more  allotropic 
forms  (see  p.  30).  As  in  the  passage  of  an  element  from  one  allotropic 
condition  to  another,  absorption  or  liberation  of  heat  always  takes  place, 
as  the  result  of  "  interior  work  ; "  it  is  more  than  probable  that  these 
perturbations  are  due  to  a  constant  tendency  of  the  element  to  pass  from 
one  allotropic  condition  to  another. 

The  atomic  heats  of  those  elementary  gases  which  have  only  been 
liquefied  by  enormous  cold  and  pressure  are  tolerably  constant  at  about 
2.4. 

Other  considerations  of  a  physical  nature  having  a  bearing  upon  the 
atomic  weights  will  be  considered  later. 

Molecular  weight. — The  molecular  weight  of  a  substance  is  the  weight 
of  its  molecule  as  compared  with  the  weight  of  an  atom  of  hydrogen.  It 
is  also,  obviously,  the  sum  of  the  weights  of  all  the  atoms  making  up  the 
molecule. 

The  determination  of  molecular  weight  is  chieijy  of  importance  in  the 
study  of  the  compounds  of  carbon.  We  can  readily  determine  the  per- 
centage composition  of  an  organic  body  by  analysis;  this  does  not, 
however,  indicate  the  number  of  atoms  of  each  of  the  constituent  ele- 


ATOMIC    AND    MOLECULAR    WJfllG-HTS VALENCE.  15 

ments.     For  example,   if  we  analyze  the  gas  acetylene,   and  the  liquid 
benzene,  we  obtain  the  following  results: 

Acetylene.        Benzene. 

Carbon 92.31         92.31         24 

Hydrogen 7.69  7.69  2 

100.00       100.00         26 

Upon  further  examination  we  find  the  molecular  weight  of  acetylene 
to  be  26,  and  consequently  we  know  its  molecule  to  consist  of  two  atoms 
of  carbon  and  two  of  hydrogen.  The  molecular  weight  of  benzene,  on  the 
other  hand,  being  78,  or  26  x  3,  we  know  that  its  molecule  consists  of  six 
atoms  each  of  carbon  and  hydrogen. 

A  very  ready  means  of  determining  the  molecular  weight  of  any  sub- 
stance which  we  can  convert  into  a  gas  is  based  upon  Avogadro's  law. 
The  specific  gravity  of  a  gas  is  the  weight  of  a  given  volume  as  compared 
with  that  of  an  equal  volume  of  hydrogen.  But  these  equal  volumes  con- 
tain equal  numbers  of  molecules  (p.  10),  and  therefor,  in  determining 
the  specific  gravity  of  a  gas,  we  obtain  the  weight  of  its  molecule  as  com- 
pared to  that  of  a  molecule  of  hydrogen;  and,  as  the  molecule  contains 
two  atoms  of  hydrogen,  while  one  atom  of  hydrogen  is  the  unit  of  com- 
parison, it  follows  that  the  specific  gravity  of  a  gas,  multiplied  by  two,  is 
its  molecular  weight. 


VALENCE,  OR  ATOMICITY. 

By  the  valence  of  an  element  is  understood  the  combining  capacity 
of  its  atoms.  We  know  that 

One  atom  of  chlorine  combines  with  one  atom  of  hydrogen, 
One  atom  of  oxygen  combines  with  two  atoms  of  hydrogen, 
One  atom  of  nitrogen  combines  with  three  atoms  of  hydrogen, 
One  atom  of  carbon  combines  with  four  atoms  of  hydrogen, 

a,nd  that  the  atoms  of  different  elements  thus  possess  different  powers  of 
holding  hydrogen  in  combination.  In  the  compounds  formed  by  the 
above  unions  chlorine  is  univalent,  oxygen  is  divalent,  nitrogen  is  trival- 
ent,  and  carbon  is  quadrivalent. 

But  the  valence  of  the  elements  is  not  fixed  and  invariable.  Thus, 
while  chlorine  and  iodine  each  combine  with  hydrogen,  atom  for  atom,  and 
in  those  compounds  are  consequently  univalent,  they  unite  with  each 
other  to  form  two  compounds — one  containing  one  atom  of  iodine  and  one 
of  chlorine,  the  other  containing  one  atom  of  iodine  and  three  of  chlorine; 
chlorine  being  univalent,  iodine  is  obviously  trivalent  in  the  second  of 
these  compounds.  Again,  phosphorus  forms  two  chlorides,  one  containing 
three,  the  other  five  atoms  of  chlorine,  to  one  of  phosphorus. 

In  view  of  these  facts,  we  must  consider,  either:  1,  that  the  valence  of 
an  element  is  that  which  it  exhibits  in  its  most  saturated  compounds,  as 
phosphorus  in  the  pentachloride,  and  that  the  lower  compounds  are  non- 
saturated  and  have  free  valences;  or  2,  that  the  valence  is  variable.  The 
first  supposition  depends  too  much  upon  the  chances  of  discovery  of  com- 
pounds in  which  the  element  has  a  higher  valence  than  that  which  might 


16  GENERAL    MEDICAL    CHEMISTRY. 

be  considered  as  the  maximum  to-day.  The  second  supposition — notwith- 
standing the  fact  that,  if  we  admit  the  possibility  of  two  distinct  valences, 
we  must  also  admit  the  possibility  of  others — is  certainly  the  more  tenable 
and  the  more  natural.  In  speaking,  therefor,  of  the  valence  of  an  ele- 
ment, we  must  not  consider  it  as  an  absolute  quality  of  its  atoms,  but 
simply  as  their  combining  power  in  the  particular  class  of  compounds 
under  consideration.  Indeed,  compounds  are  known  in  whose  molecules 
the  atoms  of  one  element  exhibit  two  distinct  valences;  thus,  ammonium 
cyanate  contains  two  atoms  of  nitrogen:  one  in  the  ammonium  group  is 
quinquivalent,  one  in  the  acid  radical  is  trivalent. 

It  has  been  found  that,  in  the  great  majority  of  instances  in  which  an 
element  exhibits  different  valences,  they  differ  from  each  other  by  two. 
Thus,  phosphorus  is  trivalent  or  quinquivalent;  platinum  is  divalent  or 
quadrivalent. 

The  valence  of  an  atom  is  expressed  in  notation  by  signs  placed  above 
and  to  the  right  of  the  symbol  (see  below),  thus:  Cl',  univalent;  O",  diva- 
lent; N'",  trivalent;  Civ,  quadrivalent;  Pv,  quinquivalent;  (Fea)vi,  hexaval- 
ent. 

Symbols — Formulae — Equations. 

Symbols. — These  are  conventional  abbreviations  of  the  names  of  the 
elements,  whose  purpose  it  is  to  introduce  simplicity  and  exactness  into 
descriptions  of  chemical  actions.  They  consist  of  the  initial  letter  of  the 
Latin  name  of  the  element,  to  which  is  usually  added  one  of  the  other 
letters.  If  there  be  more  than  two  elements  whose  names  begin  with  the 
same  letter,  the  single-letter  symbol  is  reserved  for  the  commonest  ele- 
ment. Thus,  we  have  nine  elements  whose  names  begin  with  C;  of  these 
the  commonest  is  Carbon,  whose  symbol  is  C;  the  others  have  double- 
letter  symbols,  as  Chlorine,  Cl;  Cobalt,  Co;  Copper,  Cu  (Cuprum),  etc. 

These  symbols  do  not  indicate  simply  an  indeterminate  quantity,  but 
one  atom  of  the  corresponding  element.  When  more  than  one  atom  is 
spoken  of,  the  symbol  is  not  repeated,  but  the  number  of  atoms  which  it  is 
desired  to  indicate  is  written  either  before  the  symbol,  or,  in  small  figures, 
after  and  below  it;  thus,  H  indicates  one  atom  of  hydrogen;  2C1,  two 
atoms  of  chlorine;  C4,  four  atoms  of  carbon,  etc. 

Formulae. — What  the  symbol  is  to  the  element,  the  formula  is  to  the 
compound;  by  it  the  number  and  kind  of  atoms  of  which  the  molecule  of 
a  substance  is  made  up  are  indicated.  The  simplest  kind  of  formulae  are 
what  are  known  as  empirical  formulae,;  which  indicate  only  the  kind 
and  number  of  atoms  which  form  the  compound.  Thus,  HC1  indicates  a 
molecule  composed  of  one  atom  of  hydrogen  united  with  one  atom  of 
chlorine;  5H2O,  five  molecules,  each  composed  of  two  atoms  of  hydro- 
gen and  one  atom  of  oxygen,  the  number  of  molecules  being  indicated 
by  the  proper  numeral  placed  before  the  formula,  in  which  place  it  applies 
to  all  the  symbols  following  it.  Sometimes  it  is  desired  that  a  numeral 
shall  apply  to  a  part  of  the  following  symbols  only,  in  which  case  they 
are  enclosed  in  parentheses,  thus:  3(SO4)A12,  means  3  times  SO4  arid 
twice  Al.  This  may  also  be  written  (SO4)3A12. 

For  the  other  varieties  of  formulae,  see  p.  23. 

Equations  are  combinations  of  formulae  and  algebraic  signs  so  arranged 
as  to  indicate  a  chemical  reaction  and  its  results.  The  signs  vised  are  the 
plus  and  equality  signs;  the  former  being  equivalent  to  "and,"  and  the 
second  meaning  "  have  reacted  upon  each  other  and  have  produced."  The 


RADICALS ACIDS BASES    AND    SALTS.  1 

substances  entering  into  the  reaction  are  placed  before  the  equality  sign 
and  the  products  of  the  reaction  after  it;  thus,  the  equation 

2KHO  +  S04H2=S04K2+2H20 

means,  when  translated  into  ordinary  language:  two  molecules  of  pot- 
ash, each  composed  of  an  atom  of  potassium,  one  atom  of  hydrogen  and 
one  atom  of  oxygen,  and  one  molecule  of  sulphuric  acid,  composed  of 
one  atom  of  sulphur,  four  atoms  of  oxygen  and  two  atoms  of  hydrogen, 
have  reacted  upon  each  other  and  have  produced  one  molecule  of  potas- 
sium sulphate,  composed  of  one  atom  of  sulphur,  four  atoms  of  oxygen 
and  two  atoms  of  potassium,  and  two  molecules  of  water,  each  composed 
of  two  atoms  of  hydrogen  and  one  atom  of  oxygen.  The  saving  of  time 
and  labor  by  the  use  of  symbols  is  obvious  from  this  example.  As  no 
material  is  ever  lost  or  created  in  a  reaction,  the  number  of  each  kind  of 
atom  occurring  before  the  equality  sign  in  an  equation  must  always  be 
the  same  as  that  occurring  after  it. 


Radicals — Acids — Bases  and  Salts. 

Radicals. — In  the  molecules  of  compound  substances  the  atoms  are 
not  placed  at  random,  but  certain  of  them  are  attached  more  closely  to 
each  other  than  they  are  to  the  remainder;  and  most,  if  not  all,  com- 
pounds contain  within  the  molecule  a  group  of  atoms,  whose  valences 
are  not  all  satisfied,  and  in  which  the  atoms  are  so  closely  linked  that  the 
entire  group  is  capable  of  passing  readily  from  one  combination  to  an- 
other unchanged,  although  it  is  not  necessarily  capable  of  a  separate 
existence;  such  a  group  is  called  a  radical.  Marsh-gas,  for  instance,  has 
the  empirical  formula  CH4.  By  acting  upon  this  substance  in  suitable 
ways,  we  can  cause  the  atom  of  carbon,  accompanied  by  three  of  the 
hydrogen  atoms,  to  pass  unchanged  into  a  variety  of  other  substances, 
such  as:  (CH3)C1;  (CH3)OH;  (CH3)2O;  C2H3O2  (CH3),  etc.;  we  therefor 
consider  marsh-gas  as  made  up  of  the  radical  (CH3)  combined  with  an 
atom  of  hydrogen,  (CH3)H.  It  is  usual  to  enclose  the  radical  in  brackets 
or  parentheses  to  indicate  its  nature. 

Like  the  elements,  the  radicals  possess  different  valences,  depending 
upon  the  number  of  unsatisfied  elementary  valences  which  they  contain. 
Thus,  in  the  radical  (CH3)  three  of  the  four  valences  of  the  atom  of  car- 
bon are  satisfied  by  three  atoms  of  hydrogen;  the  remaining  free  valence 
of  the  carbon  atom  renders  the  radical  univalent;  it  gives  it  a  power  of 
combination  equal  to  that  of  an  atom  of  a  univalent  element.  These 
radicals  play  an  important  part  in  the  chemistry  of  the  carbon  compounds. 

Acids. — It  is  a  difficult  matter  to  give  a  concise  definition  of  an  acid, 
which  shall  cover  the  meaning  fully.  The  usual  definition  is  "  a  compound 
of  an  electro-negative  radical  with  hydrogen,  which  hydrogen  it  can  part 
with  in  exchange  for  a  metal  or  basylous  radical,"  which  is  probably  as 
satisfactory  a  definition  as  can  be  given  at  present.  The  two  character- 
istics of  an  acid  being  that  it  contains,  on  the  one  hand,  an  electro-nega- 
tive radical  or  element,  and,  on  the  other  hand,  hydrogen  capable  of  being 
replaced  by  an  electro-positive  radical  or  element.  The  atoms  of  hydro- 
gen so  replaceable  are  termed  the  basic  or  replaceable  hydrogen  of  the 
acid,  the  acid  itself  being  designated  as  monobasic,  dibasic,  tribasic,  te- 
trabasic,  etc.,  according  as  it  contains  one,  two,  three,  four,  etc.,  atoms  of 
such  replaceable  hydrogen. 
2 


18 


GENERAL    MEDICAL    CHEMISTRY. 


By  electropositive  or  basylous  elements  or  radicals  are  meant  such  as 
are  disengaged  at  the  zinc  or  negative  pole,  when  their  compounds  are 
decomposed  by  the  action  of  the  galvanic  battery. 

By  electro-negative  or  acidulous  are  meant  such  as  are  disengaged  at 
the  platinum  or  positive  pole  under  like  circumstances.  In  the  following 
table  are  given  the  electric  conditions  of  the  more  important  elements  and 
radicals: 


ELECTRO-POSITIVE,  OR  BASYLOUS. 

ELECTRO-NEGATIVE,  OR  ACIDULOUS. 

Hydrogen. 

Copper. 

Oxygen. 

Arsenic. 

Potassium. 

Mercury. 

Fluorine. 

Antimony. 

Sodium. 

Tin. 

Chlorine. 

Boron. 

Lithium. 

Iron. 

Bromine. 

Carbon. 

Silver. 

Cobalt. 

Iodine. 

Silicium. 

Ammonium. 

Nickel. 

Sulphur. 

Molybdenum. 

Calcium. 

Gold. 

Selenium. 

Tungsten, 

Barium. 

Bismuth. 

Tellurium. 

and  their  oxidized 

Zinc. 

Platinum. 

Nitrogen. 

radicals. 

Magnesium. 

Aluminium. 

Phosphorus. 

Cyanogen. 

Cadmium. 

Chromium. 

Lead. 

Alcoholic  radicals. 

Bases. — A  base  is  a  compound  of  hydrogen  and  oxygen  with  an  elec- 
tro-positive element  or  radical,  which  it  is  capable  of  giving  up  in  exchange 
for  the  hydrogen  of  an  acid;  indeed,  it  may  be  considered  as  one  or  more 
molecules  of  water,  in  which  one-half  the  hydrogen  has  been  replaced  by 
an  electro-positive  element  or  radical.  Thus,  KHO,  potassium  hydrate; 
(NHJHO,  ammonium  hydrate.  These  substances,  being  considered  as 
derived  from  water,  are  called  hydrates;  they  are,  according  to  existing 
views,  the  only  substances  to  which  the  term  base  properly  applies. 

Bases  and  acids  are  capable  of  what  is  called  double  decomposition, 
with  each  other.  That  is,  the  acid  and  base  are  both  decomposed,  while 
water  and  a  salt  are  formed  : 

KHO  +  NO3H  =  H2O  +  NO3K. 

Potassium        Nitric          Water.     Potassium 
hydrate.          acid.  nitrate. 

Salts  are  substances  formed  by  the  substitution  of  basylous  radicals 
or  elements  for  a  part  or  all  of  the  replaceable  hydrogen  of  an  acid. 
They  are  always  formed,  therefor,  when  bases  and  acids  enter  into 
double  decomposition.  They  are  not,  as  was  formerly  supposed,  formed 
by  the  union  of  a  metallic  with  a  non-metallic  oxide,  but,  as  stated  above, 
by  the  substitution  of  one  or  more  atoms  of  an  element  or  radical  for  the 
hydrogen  of  the  acid.  Thus,  the  compound  formed  by  the  action  of  sul- 
phuric acid  upon  quicklime  is  not  SO3CaO,  but  SO4Ca,  formed  by  the 
interchange  of  atoms 

S 


and  not 


4 

^ 

H\ 

o 

S 

O 

^ 

/Ca 

RADICALS ACIDS BASES    AND    SALTS.  19 

for  which  reason  it  is  not  the  sulphate  of  limey  as  it  was  formerly  called, 
but  calcium  sulphate. 

The  basylous  element  of  a  salt  is  endowed  with  considerable  mobility, 
and  may  be  readily  transferred  from  one  acid  radical  to  another;  or  liber- 
ated by  the  presence  of  an  acid  radical  with  which  it  has  a  greater  ten- 
dency to  unite  (for  which  it  has  a  greater  affinity),  or  of  an  element  whose 
tendency  to  unite  with  its  acidulous  radical  is  greater  than  its  own.  Thus, 
if  sodium  sulphate  and  barium  nitrate  be  brought  together  in  solution, 
the  following  double  decomposition  occurs: 

SO4Na2  +  (NO3)2Ba = SO4Ba + 2NO3Na. 

Again,  silver  is  separated  from  the  nitrate  by  the  presence  of  mercury; 
lead  from  its  acetate  in  the  presence  of  zinc;  copper  from  its  sulphate  in 
the  presence  of  iron,  etc. 

If  two  acids  be  brought  in  the  presence  of  a  single  base,  the  latter  is 
divided  by  the  former  according  to  their  affinities,  subject  to  the  modifi- 
cations due  to  the  volatility  of  the  acid,  or  its  insolubility,  or  the  insolu- 
bility of  the  salt  formed. 

If  one  of  the  acids  be  volatile  at  the  temperature  at  which  the  reac- 
tion occurs,  it  is  driven  off.  Sodium  nitrate  and  sulphuric  acid  may 
exist  together  at  ordinary  temperatures,  but  upon  heating  the  mixture 
the  nitric  acid  is  driven  off  and  sodium  sulphate  is  formed. 

If  one  of  the  acids  be  insoluble,  its  influence  becomes  nil — it  separates 
in  the  solid  form  while  the  other  takes  its  place;  thus,  if  potassium  silicate 
and  hydrochloric  acid  be  brought  together,  potassium  chloride  remains  in 
the  solution  and  silicic  acid  separates. 

Whenever  two  salts  in  solution  are  brought  together,  the  basylous 
element  of  one  of  which  is  capable  of  uniting  with  the  acidulous  radical 
of  the  other  to  form  an  insoluble  salt,  the  insoluble  compound  is  formed. 
Thus,  if  a  solution  of  a  sulphate  be  added  to  a  solution  of  a  barium  salt, 
the  insoluble  barium  sulphate  is  precipitated. 

What  has  been  stated  of  two  acids  in  presence  of  one  base  also  ap- 
plies to  two  bases  in  presence  of  one  acid. 

The  term  salt,  as  used  at  present,  applies  to  the  compound  formed  by 
the  substitution  of  another  element  for  the  hydrogen  of  any  acid;  and 
indeed,  as  used  by  some  authors,  to  the  acids  themselves,  which  are  con- 
sidered as  salts  of  hydrogen.  It  is  probable,  however,  that  eventually 
the  name  will  be  limited  to  such  compounds  as  correspond  to  acids  whose 
molecules  contain  more  than  two  elements.  Indeed,  from  the  earliest 
times  of  modern  chemistry,  a  distinction  was  observed  between  the  haloid 
salts,  i.  6.,  those  the  molecules  of  whose  corresponding  acids  consisted  of 
hydrogen  united  with  one  other  element,  on  the  one  hand;  and  the  salts 
of  the  oxacids,  i.  e.9  those  into  whose  composition  oxygen  entered,  on  the 
other  hand.  This  distinction,  however,  has  gradually  fallen  into  the  back- 
ground, for  the  reason  that  the  methods  and  conditions  of  formation  of 
the  two  kinds  of  salts  are  usually  the  same  when  the  basylous  element  be- 
longs to  that  class  of  elements  usually  designated  as  metallic. 

There  are,  nevertheless,  important  distinctions  between  the  two  kinds 
of  salts,  which  we  believe  to  be  of  sufficient  importance  not  only  to  men- 
tion, but  to  make  a  factor  in  the  classification  of  the  elements  (see  p.  26). 
The  salts  of  the  hydracids  (haloid  salts)  maybe  readily  obtained  without 
the  previous  formation  of  the  acid,  as  potassium  unites  directly  with 
chlorine  to  form  potassium  chloride.  The  salts  of  the  oxacids,  on  the 


20  GENERAL    MEDICAL    CHEMISTRY. 

other  hand,  are  only  formed  by  the  substitution  of  the  basylous  element 
for  the  hydrogen  of  the  previously  formed  acid,  by  some  double  decom- 
position or  by  the  oxidation  of  an  existing  compound,  in  all  cases  in  which 
the  corresponding  acid  is  capable  of  separate  existence.  There  are,  for 
example,  three  methods  of  formation  of  potassium  sulphate:  either  by  the 
action  of  the  basylous  element  or  its  hydrate  upon  sulphuric  acid  — 


S04H2+K2        =  S04 

S04H2  +  2KHO  =  S04K2  +  2HtO  ; 

or  by  double  decomposition  — 

2NO3K  +  SO4H2  =  SO4K2  -f  2NO3H  ; 
or  by  the  oxidation  of  the  sulphide  — 


In  those  cases  in  which  the  acid  corresponding  to  the  salt  has  not 
been  obtained,  it  is  more  than  probable  that  the  formation  of  the  acid 
precedes  that  of  the  salt.  The  true  carbonic  acid,  for  instance,  C03H2,  is 
not  known,  yet  its  anhydride,  CO2,  is  capable  of  forming  salts;  but,  as  the 
formation  of  these  salts  occurs  only  in  the  presence  of  water,  we  may  infer 
that  the  reaction 

C02  +  H20=C03H2 

occurs  before  the  formation  of  the  salt. 

An  important  difference  between  the  two  classes  of  compounds,  and 
one  which  we  have  utilized  in  our  classification  of  the  elements,  is  that, 
while  there  exist  \compounds  of  all  the  elements  corresponding  to  the 
hydracids,  there  are  many  elements  which  are  not  capable  of  replacing 
the  hydrogen  of  the  oxacids  to  form  salts;  and  those  elements,  thus  in- 
capable of  forming  oxysalts,  are  strongly  electro-negative,  and  their  ox- 
ides are  capable  of  uniting  with  water  to  form  acids  (see  p.  27). 


Nomenclature. 

The  names  of  the  elements  are  mostly  of  Greek  derivation,  and  have 
their  origin  in  some  prominent  property  of  the  substance;  thus,  phos- 
phorus, «£cos,  light,  and  <£e'peiv,  to  bear.  Some  are  of  Latin  origin,  as  silicon, 
from  silex,  flint;  some  of  Gothic  origin,  as  iron,  from  iam;  and  others  are 
derived  from  modern  languages,  as  potassium,  from  pot-ash.  Very  little 
system  has  been  followed  in  naming  the  elements,  beyond  applying  the 
termination  ium  to  the  metals,  and  ine  or  on  to  the  metalloids;  and  even 
to  this  rule  we  find  such  exceptions  as  a  metal  called  manganese  and  a 
metalloid  called  sulphur. 

The  names  of  compound  substances  were  formerly  chosen  upon  the 
same  system,  or  rather  lack  of  system,  as  those  of  the  elements.  So  long 
as  the  number  of  compounds  with  which  the  chemist  had  to  deal  remained 
small,  the  use  of  these  fanciful  appellations,  conveying  no  more  to  the 
mind  than  perhaps  some  unimportant  quality  of  the  substances  to  which 
they  applied,  gave  rise  to  comparatively  little  inconvenience.  In  these 
later  days,  however,  when  the  number  of  compounds  has  risen  high  in  the 
thousands,  some  systematic  method  has  become  absolutely  necessary. 


ISTOMENCL  ATUKE.  2 1 

The  principle  at  the  base  of  the  system  of  nomenclature  at  present  used 
is  that  the  name  shall  itself  convey,  as  far  as  possible,  the  composition  and 
character  of  the  substance. 

Compounds  consisting  of  two  elements,  or  of  an  element  and  a  radical 
only,  binary  compounds,  are  designated  by  compound  names  made  up  of 
the  name  of  the  more  electro-positive,  followed  by  that  of  the  more  elec- 
tro-negative, in  which  the  termination  ide  has  been  substituted  for  the 
terminations  ine,  on,  ogen,  ygen,  orus,  ium,  and  itr.  For  example:  the 
compound  of  potassium  and  chlorine  is  called  potassium  chloride,  that  of 
potassium  and  oxygen,  potassium  oxide,  that  of  potassium  and  phos-. 
phorus,  potassium  phosphide. 

In  a  few  instances  the  older  name  of  a  compound  is  used  in  preference 
to  the  one  which  it  should  have  under  the  above  rule,  for  the  reason  that 
the  substance  is  one  which  is  typical  of  a  number  of  other  substances, 
and  therefor  deserving  of  exceptional  prominence;  such  are  ammonia, 
NH3 ;  water,  H2O. 

When,  as  frequently  happens,  two  elements  unite  with  each  to  form 
more  than  one  compound,  these  are  usually  distinguished  from  each  other 
by  prefixing  to  the  last  word  of  the  name  the  Greek  numeral  correspond- 
ing to  the  number  of  atoms  of  the  element  designated  by  that  word,  as 
compared  with  a  fixed  number  of  atoms  of  the  other  element. 

Thus,  in  the  series  of  compounds  of  nitrogen  and  oxygen,  most  of 
which  contain  two  atoms  of  nitrogen,  N2  is  the  standard  of  comparison, 
and  consequently  the  names  are  as  follows: 

N2O  —Nitrogen  monoxide. 

NO  (  =  N2O2)  =  Nitrogen  dioxide. 
N2O3  =  Nitrogen  trioxide. 

N2O  (=N2O4)= Nitrogen  tetroxide. 

N2O5  =  Nitrogen  pentoxide. 

« 

Another  method  of  distinguishing  two  compounds  of  the  same  two 
elements  consists  in  terminating  the  first  word  in  ous  in  that  compound 
which  contains  the  less  proportionate  quantity  of  the  more  electro -nega- 
tive element,  and  in  ic  in  that  containing  the  greater  proportion;  thus: 

SO2  =  Sulphurous  oxide. 
SO3^=  Sulphuric  oxide. 

Hg2Cl2  (2Hg  :  2Cl)=Mercurow*  chloride. 
HgCl2  (2Hg  :  4C1)  =Mercurfc  chloride. 

This  method,  although  used  to  a  certain  extent  in  speaking  of  compounds 
composed  of  two  elements  of  Class  II.  (see  p.  27),  is  used  chiefly  in  speak- 
ing of  binary  compounds  of  elements  of  different  classes. 

In  naming  the  oxacids  the  word  acid  is  used,  preceded  by  the  name 
of  the  electro-negative  element  other  than  oxygen,  to  which  a  prefix  or 
suffix  is  added  to  indicate  the  degree  of  oxidation.  If  there  be  only  two, 
the  least  oxidized  is  designated  by  the  suffix  ous,  and  the  more  oxidized 
by  the  suffix  ic,  thus: 

NO2H=Nitr<ms  acid. 
NO,H=Nitricacid< 

If  there  be  more  than  two  acids,  formed  in  regular  series,  the  least  oxi- 


22  GENERAL    MEDICAL    CHEMISTRY. 

dized  is  designated  by  the  prefix  hypo  and  the  suffix  ous;  the  next  by  the 
suffix  ous;  the  next  by  the  suffix  ic;  and  the  most  highly  oxidized  by  the 
prefix  per  and  the  suffix  ic;  thus: 

C1OH  —Hypochloious  acid. 
ClO2H=Chloroz^  acfd. 
ClO3H=Chlo«c  acid. 
C1O4H= Perchloric  acid. 

Certain  elements,  such  as  sulphur  and  phosphorus,  exist  in  acids  which 
are  derived  from  those  formed  in  the  regular  way,  and  which  are  specially 
designated  (see  pp.  88,  112). 

The  names  of  the  salts  are  derived  from  those  of  the  acids  by  drop- 
ping the  word  acid,  changing  the  termination  of  the  other  word  from  ous 
into  ite,  or  from  ic  into  ate,  and  prefixing  the  name  of  the  electro-positive 
element  or  radical;  thus: 

SO3H2  S03K2 

Sulphnrow*  acid.  Potassium  sulphate. 

SO.H,  S04K2 

Sulphuric  acid.  Potassium  sulphate. 

C1OH  C1OK 

HypochloroMs  acid.  Potassium  hypochlon'te. 

Acids  whose  molecules  contain  more  than  one  atom  of  replaceable  hy- 
drogen are  capable  of  forming  more  than  one  salt  with  electro-negative 
elements,  or  radicals,  whose  valence  is  less  than  their  basicity.  Ordinary 
phosphoric  acid,  for  instance,  contains  in  each  molecule  three  atoms  of 
basic  hydrogen,  and  consequently  is  capable  of  forming  three  salts  by  the 
replacement  of  one,  two,  or  three  of  its  hydrogen  atoms  by  one,  two,  or 
three  atoms  of  a  univalent  element;  to  distinguish  these  the  Greek  pre- 
fixes mono,  di,  and  tri  are  used  thus: 

PO4H2K = j$fo»0potasfiic  phosphate. 
PO4HK2n:7>£potassic  phosphate. 
PO4K3     =  TKpotassic  phosphate. 

The  first  is  also  called  dihydropot&ssic  phosphate,  and  the  second  hydrodi- 
potassic  phosphate. 

In  the  older  works,  salts  in  which  the  hydrogen  has  not  been  entirely 
displaced  are  sometimes  called  fo'salts  (bicarbonates),  or  acid  salts;  those 
in  which  the  hydrogen  has  been  entirely  displaced  being  designated  as- 
neutral  salts. 

A  few  elements,  such  as  mercury,  copper,  and  iron,  form  two  distinct 
series  of  salts;  these  are  distinguished,  in  the  same  way  as  the  acids,  by 
the  use  of  the  suffix  ous  in  the  names  of  those  containing  the  less  propor- 
tion of  electro-negative  group  and  the  suffix  ic  in  those  containing  the 
greater  proportion,  e.  g.  : 

SO4(Cu2)2 (1SO4  :  4Cu)=Cuprow»  sulphate, 

SO4  Cu2      (2SO4  :  4Cu)  =  Cupr»c  sulphate. 

SO4Fe         (2SO4  :  2Fe)=Femws  sulphate. 

(SO4)3Fe2    (3SO4  :  2Fe)— Feme  sulphate. 

The  names,  basic  salts,  subsalts,  and  cwysalts  have  been  applied  in- 
differently to  salts,  such  as  the  lead  subacetates,  which  are  compounds- 


TYPICAL    FORMULAE    AND    FORMULAE    OF   CONSTITUTION.        23 

containing  the  normal  acetate  and  the  hydrate  or  oxide  of  lead;  and  to 
salts  such  as  the  so-called  bismuth  subnitrate,  which  is  a  nitrate,  not  of 
bismuth,  but  of  the  univalent  radical  (Bi'"O")'. 

By  double  salts  are  meant  such  as  are  formed  by  the  substitution  of 
different  elements  or  radicals  for  two  or  more  atoms  of  replaceable  hydro- 
gen of  the  acid,  such  as  ammonio-magnesian  phosphate,  PO4Mg"  (NH4)'. 


Oxides,  Hydrates,  and  Chlorides. 

The  oxides,  hydrates,  and  chlorides  of  the  various  elements  differ 
from  each  other  materially  in  their  properties.  The  oxides  of  a  certain 
class  of  elements,  when  they  unite  with  water,  form  hydrates  which  pos- 
sess acid  properties;  such  oxides  are  called  anhydrides.  The  oxides  of 
another  class  of  elements  unite  with  water  to  form  hydrates  endowed  with 
strongly  basic  properties.  Between  these  two  classes  is  a  third,  some 
of  whose  oxides  form  hydrates  which  are  basic  in  character,  while  others 
unite  with  water  to  form  acids  (see  p.  27). 

As  a  rule,  those  elements  which  form  basic  hydrates  also  form  chlo- 
rides which  are  either  insoluble  in  water,  or  soluble  without  decomposition. 
Those  elements,  on  the  other  hand,  whose  oxides  are  all  anhydrides,  form 
chlorides  which  are  decomposed  when  they  come  in  contact  with  water. 


Typical  Formulae  and  Formulae  of  Constitution. 

The  formulas  which  we  have  hitherto  used,  and  which  are  known  as 
empirical  formulae,  indicate  only  the  number  and  kind  of  atoms  consti- 
tuting the  molecule — indications  which  would  seem  at  first  sight  to  be  all 
that  could  be  required  of  them.  When,  however,  it  was  found  that  two 
substances  existed,  each  composed  of  the  same  kind  and  number  of  atoms, 
and  yet  possessing  very  different  physical  and  chemical  properties,  the 
inference  naturally  followed  that  these  differences  must  be  due  to  a  dif- 
ferent arrangement  of  the  atoms  within  the  molecule — a  different  consti- 
tution^ as  it  is  called.  To  indicate  these  differences  extended  formulse 
were  devised:  typical  formulae,  which  show  only  the  more  salient  points 
of  the  constitution  of  the  substance;  and  graphic  formitlce,  or  formulae 
of  constitution,  which  are  intended  to  set  forth  the  entire  structure  of  the 
molecule. 

The  idea  of  chemical  types  was  first  suggested  by  Dumas  in  1839.  In 
the  system  of  typical  formulae  all  substances  are  considered  as  being-  so 
constituted  that  their  rational  formulae  may  be  referred  to  one  of  three 
classes  or  types,  or  to  a  combination  of  two  of  these  types.  These  three 
classes,  beinsr  named  after  the  most  common  substance  occurring  in  each, 
are  expressed  thus: 

The  hydrogen  The  water  The  ammonia 

type.  type.  type. 

H)  H)O  in 

HC  HfC  H^N 

H 


etc.,  etc.,  H 

etc., 


24  GENERAL    MEDICAL    CHEMISTRY. 

it  being  considered  that  the  formula  of  any  substance  of  known  consti- 
tution can  be  indicated  by  substituting  the  proper  element,  or  radical,  for 
one  or  more  of  the  atoms  of  the  type,  thus: 


01)        (C2H5)'|0       (C2HJM  (V(        (SO,)") 

Hf  HfC  HV-N       Caf  HJO, 

H) 


Hydrochloric  Alcohol.  Bthylamine.          Calcium  Sulphuric  Urea, 

acid.  chloride.  acid. 

Typical  formulae  are  of  great  service  in  the  classification  of  compound 
substances,  as  well  as  to  indicate,  to  a  certain  degree,  their  nature  and 
the  method  of  the  reactions  into  which  they  enter. 

Referring,  for  instance,  to  the  formula  of  marsh-gas,  given  on  p.  17, 
as  (CH  )  H,  we  find  that  it  belongs  to  the  same  type  as  hydrogen,  and 

OH    ) 
that  its  typical  formula  is       j|  r  •     This  formula  indicates  not  only  that 

the  substance  is  composed  of  the  univalent  radical  CH3  with  an  atom  of 
hydrogen,  but  also  that  the  extra-radical  atom  of  hydrogen,  being  united 
to  an  electro-positive  radical,  is  not  replaceable  after  the  manner  of  the 
basic  hydrogen  of  an  acid,  although  it  may  be  replaced  by  an  electro- 
negative element,  such  as  chlorine.  The  radical  CH3  is  also*  capable  of 
removal  and  passage  into  other  forms  of  combination;  it  may  be  made  to 

OH  CH    ) 

pass  from  the  compound      JT  [   into  that  having  the  composition      Q|  !• , 

CH    ) 
and    from    that    into       TT  !•  O.    The   last   formula   indicates   a   substance 

which  is  of  the  same  type  as  water,  and  is  consequently  the  hydrate  of 
the  radical,  a  hydrate  which,  owing  to  the  electro-positive  character  of 
the  radical,  is  not  acid.  If,  however,  the  radical  be  oxidized,  it  becomes 

electro-negative,  and  the  resulting  substance,  ^          A  j-  O,  is  endowed  with 

acid  properties,  and,  as  the  tvpical  formula  indicates,  contains  a  single 
atom  of  basic  hydrogen. 

There  are  two  substances  which,  on  analysis,  each  prove  to  have  the 
composition  C2H4O2,  and  which,  nevertheless,  differ  from  each  other 
widely  in  their  properties.  By  a  further  examination  of  these  two  sub- 
stances, we  find  that  one  contains  the  group  (CH3)',  while  the  other  con- 
tains the  group  (C2H3O)',  united  to  one  atom  of  replaceable  hydrogen. 
The  difference  in  their  constitution  at  once  becomes  apparent  in  their 

typical  formulae,  ^^t  \  O  and  (C*H3°^  I  O,  which  also  indicate  differ- 
ences in  their  properties,  which  we  find  upon  experiment  to  exist.  The 
first  substance  is  neutral  in  reaction  and  possesses  no  acid  properties;  it 

/pTTQ\     \ 

closely  resembles  a  salt  of  an  acid  having  the  formula  ^         TT  [•  O.     The 

second  substance,  on  the  other  hand,  has  a  strongly  acid  reaction,  and 
markedly  acid  properties,  as  indicated  by  the  oxidized  radical  and  the 
extra-radical  hydrogen.  It  is  capable  of  forming  salts  by  the  substitution 
of  an  atom  of  a  univalent  basylous  element  for  its  single  replaceable  atom 

^O  TT  OV  ) 
of  hydrogen  ^    2    3-,v    t  O.     Again,  the  action  which  takes  place  between 

caustic  potash  and  acetic  acid  is  indicated  more  accurately  and  intelli- 
gibly by  the  typical  equation — 


TYPICAL    FORMULAE    AND    FORMULAE    OF  CONSTITUTION.        25 

,      =     H)Q  CaH30 

n  \  J\. 

than  by  the  empirical  equation — 


Although  typical  formulae  have  been,  and  still  are,  of  great  service, 
many  cases  arise,  especially  in  treating  of  the  more  complex  organic  sub- 
stances, in  which  they  do  not  sufficiently  indicate  the  relations  between 
the  atoms  which  constitute  the  molecule,  and  thus  fail  to  convey  a  proper 
idea  of  the  nature  of  the  substance.  Considering,  for  example,  the  ordi- 
nary lactic  acid,  we  find  its  composition  to  be  C_H  O  ,  which,  expressed 

(G  H  OV  ) 
typically,  would  be  ^    3     4  tr    [  O2>  a  constitution  supported  by  the  fact 

that    the    radical    (C3H4O)"    may  be    obtained    in   other  compounds,   as 

(C*  TT  OV  ) 

^3    4  Xi    j- .    This  constitution,  however,  cannot  be  the  true  one,  because 

in  the  first  place,  lactic  acid  is  not  dibasic,  but  monobasic;  and,  in  the 
second  place,  there  is  another  acid,  called  paralactic  acid,  having  an  iden- 
tical composition,  yet  differing  in  its  products  of  decomposition.  These 
differences  in  the  properties  of  the  two  acids  must  be  due  to  a  different 
arrangement  of  atoms  in  their  molecules,  a  view  which  is  supported  by 
the  sources  from  which  they  are  obtained  and  the  nature  of  their  products 
of  decomposition. 

To  express  the  constitution  of  such  bodies,  graphic  formulas  are  used, 
in  which  the  position  of  each  atom  in  relation  to  the  others  is  set  forth. 
The  constitution  of  the  two  lactic  acids  would  be  expressed  by  graphic 
formulae  in  this  way: 


Cf-H 
XO— H 

and         t/v  T. 

I/O 
C\0— H 

CH3  CH2OH 


CH. 
CO. 


OH        and 

OH  CO.OH 

Ordinary  Paralactic 

lactic  acid.  acid. 

It  must  be  understood  that  these  graphic  formulae  are  simply  in- 
tended to  show  the  relative  attachments  of  the  atoms,  and  are  in  nowise 
intended  to  convey  the  idea  that  the  molecule  is  spread  out  upon  a  flat 
surface  with  the  atoms  arranged  as  indicated  in  the  diagram.  The  for- 
mula of  ordinary  lactic  acid  shows  that  one  of  its  atoms  of  carbon  has 
three  of  its  valences  satisfied  by  three  atoms  of  hydrogen,  and  is  attached 
by  its  remaining  valence  to  another  atom  of  carbon,  one  of  whose  other 


26  GENERAL    MEDICAL    CHEMISTRY. 

valences  is  satisfied  by  an  atom  of  hydrogen,  another  by  the  univalent 
group  OH,  and  whose  remaining  valence  attaches  it  to  the  third  atom 
of  carbon,  two  of  whose  remaining  valences  are  satisfied  by  one  atom  of 
the  divalent  element  oxygen,  and  the  last  by  the  group  OH. 

Great  care  and  much  labor  are  require^  in  the  construction  of  these 
graphic  formula?,  the  positions  of  the  atoms  being  determined  by  a  close 
study  of  the  methods  of  formation,  and  of  the  products  of  decomposition 
of  the  substance  under  consideration.  Naturally,  in  a  matter  of  this  na- 
ture, there  is  always  room  for  differences  of  opinion — indeed,  the  entire 
atomic  theory  is  open  to  question,  as  is  the  theory  of  gravitation  itself; 
but,  whatever  may  be  advanced,  two  facts  cannot  be  denied  :  first,  that 
chemistry  owes  its  advancement  within  the  past  half-century  to  the  atomic 
theory,  which  to-day  is  more  in  consonance  with  observed  facts  than  any 
substitute  which  can  be  offered  ;  second,  that  without  the  use  of  graphic 
formulae  it  would  be  impossible  to  offer  any  adequate  explanation  of  the 
reactions  which  we  observe  in  dealing  with  the  more  complex  org*anic  sub- 
stances. 

In  chemistry,  as  in  other  sciences,  a  sharp  distinction  must  always  be 
made  between  facts  and  theory:  the  former,  once  observed,  are  immut- 
able additions  to  our  knowledge;  the  latter  are  of  their  nature  subject  to 
change  with  our  increasing  knowledge  of  facts.  We  have  every  reason 
for  believing,  however,  that  the  supports  upon  which  the  atomic  theory 
rests  are  such  that,  although  it  may  be  modified  in  its  details,  its  essential 
features  will  remain  unaltered. 


Classification  of  the  Elements. 

The  necessity  of  a  classification  of  the  elements  into  groups  for  con- 
venience of  study  was  felt  early  in  the  history  of  chemistry.  Berzelius 
was  the  first  to  divide  all  the  elements  into  two  great  classes,  to  which  he 
gave  the  names  metals  and  metalloids.  The  metals,  being  such  substances 
as  are  opaque,  possess  what  is  known  as  metallic  lustre,  are  good  con- 
ductors of  heat  and  electricity,  and  are  electro-positive;  the  metalloids, 
on  the  other  hand,  such  as  are  gaseous,  or,  if  solid,  do  not  possess  metallic 
lustre,  have  a  comparatively  low  power  of  conducting  heat  and  electri- 
city, and  are  electro-negative. 

This  division,  based,  as  it  will  be  seen,  purely  upon  physical  proper- 
ties, which,  in  many  cases,  are  ill-defined,  has  become  insufficient.  Sev- 
eral elements  formerly  classed  under  the  above  rules  with  the  metals,  such 
as  arsenic  and  antimony,  resemble  phosphorus  in  their  chemical  characters 
much  more  clearly  than  they  do  any  of  the  metals;  indeed,  by  the  char- 
acters mentioned  above,  it  is  impossible  to  draw  any  line  of  demarcation 
which  shall  separate  the  elements  distinctly  into  two  groups. 

The  classification  of  the  elements  should  be  such  that  each  group  shall 
•contain  elements  whose  chemical  properties  are  similar — the^Aysz'cc//  prop- 
erties being  considered  only  in  so  far  as  they  are  intimately  connected  with 
the  chemical  (see  p.  13).  The  arrangement  of  elements  into  groups  is  not 
equally  easy  in  all  cases;  some  groups,  as  the  chlorine  group,  are  sharply 
defined,  while  the  members  of  others  differ  from  each  other  more  widely 
in  their  properties.  The  positions  of  most  of  the  more  recently  discovered 
elements  are  still  uncertain,  owing  to  the  imperfect  state  of  our  knowl- 
edge of  their  properties. 

The  method  of  classification  which  we  will  adopt,  and  which  we  believe 


CLASSIFICATION    OF    TIIE    ELEMENTS.  27 

to  be  more  natural  than  any  hitherto  suggested,  is  based  upon  the  chem- 
ical properties  of  the  oxides  and  upon  the  valence  of  the  elements.  We 
would  abandon  entirely  the  division  into  metals  and  metalloids,  and  sub- 
stitute for  it  a  division  into  four  great  classes,  according  to  the  nature  of 
the  oxides  and  the  existence  or  non-existence  of  oxysalts.  In  the  first  of 
these  classes  hydrogen  and  oxygen  are  placed  together,  for  the  reason  that, 
although  they  differ  from  each  other  in  many  of  their  properties,  they  to- 
gether form  the  basis  of  our  classification,  and  may,  for  this  and  other 
reasons,  be  regarded  as  typical  elements.  They  both  play  important 
parts  in  the  formation  of  acids,  and  neither  would  find  a  suitable  place  in 
either  of  the  other  classes.  Our  primary  division  would  then  be  as  follows: 

Class  I. — Typical  elements. 

Class  H. — Elements  whose  oxides  unite  with  water  to  form  acids,  never 
to  form  bases.  Which  do  not  form  oxysalts. 

This  class  contains  all  the  so-called  metalloids  except  hydrogen  and 
oxygen. 

Class  III. — Elements  whose  oxides  unite  with  water,  some  to  form 
bases,  others  to  form  acids.  Which  form  oxysalts. 

Class  IV. — Elements  whose  oxides  unite  with  water  to  form  bases  ; 
never  to  form  acids.  Which  form  oxysalts. 

In  this  class  are  included  the  more  strongly  electro-positive  metals. 

Within  the  classes  a  further  subdivision  is  made  into  groups,  each 
group  containing  those  elements  within  the  class  which  have  equal  valen- 
ces, which  form  corresponding  compounds,  and  whose  chemical  charac- 
ters are  otherwise  similar. 


GROUP  I. — Hydrogen. 
GROUP  II. — Oxygen. 


Class  I. 


Class 


GROUP  I. — Fluorine,  chlorine,  bromine,  iodine. 

GROUP  II. — Sulphur,  selenium,  tellurium. 

GROUP  III. — Nitrogen,  phosphorus,  arsenic,  antimony. 

GROUP  IV. — Boron. 

GROUP  V. — Carbon,  silicon. 

GROUP  VI. — Vanadium,  niobium,  tantalium. 

GROUP  VII. — Molybdenum,  tungsten,  osmium  (?). 

Class  in. 

GROUP  I. — Gold. 

GROUP  II. — Chromium,  manganese,  iron. 

GROUP  III. — Aluminium,  gallium  (?),  indium  (?),  glucinium. 

GROUP  IV. — Uranium. 

GROUP  V. — Lead. 

GROUP  VI. — Bismuth. 

GROUP  VII. — Titanium,  zirconium,  tin. 

GROUP  VIII. — Palladium,  platinum. 

GROUP  IX. — Rhodium,  ruthenium,  iridium. 


"28  GENERAL    MEDICAL    CHEMISTRY. 

Class  IV. 

GROUP  I. — Lithium,  sodium,  potassium,  rubidium,  caesium,  silver. 

GROUP  II. — Thallium. 

GROUP  III. — Calcium,  strontium,  barium. 

GROUP  IV. — Magnesium,  ziiic,  cadmium. 

GROUP  V. — Nickel,  cobalt. 

GROUP  VI. — Copper,  mercury. 

GROUP  VII. — Yttrium,  cerium,  lanthanium,  didymium,  erbium. 

GROUP  VIII.— Thorium. 


Physical  Characters  of  Chemical  Interest. 

CRYSTALLIZATION. — Solid  substances  exist  in  two  forms,  amorphous 
,and  crystalline.  In  the  former  they  assume  no  definite  geometrical 
shape  ;  they  conduct  heat  equally  well  in  all  directions  ;  they  break 
irregularly;  and,  if  transparent,  allow  light  to  pass  through  them  equally 
well  in  all  directions.  A  solid  in  the  crystalline  form  has  a  definite  geo- 
metrical shape  ;  conducts  heat  more  readily  in  some  directions  than  in 
others;  when  broken,  separates  in  certain  directions,  called  planes  of 
cleavage,  more  readily  than  in  others;  and  modifies  the  course  of  lumi- 
nous rays  passing  through  it  differently  when  they  pass  in  certain  direc- 
tions than  when  they  pass  in  others. 

Crystals  are  formed  in  one  of  four  ways  :  1,  an  amorphous  substance, 
by  slow  and  gradual  modification,  may  assume  the  crystalline  form,  as 
vitreous  arsenic  trioxide  (q.  v.)  passes  to  the  crystalline  variety.  2,  a 
fused  solid,  on  cooling,  crystallizes,  as  bismuth.  3,  when  a  solid  is  sub- 
limed it  is  usually  condensed  in  the  form  of  crystals.  Such  is  the  case 
with  arsenic  trioxide.  4,  the  usual  method  of  obtaining  crystals  is  by 
the  evaporation  of  a  solution  of  the  substance.  If  the  evaporation  be 
.slow  and  the  solution  at  rest,  the  crystals  are  large  and  well-defined.  If 
the  crystals  separate  by  the  sudden  cooling  of  a  hot  solution,  especially 
if  it  be  agitated  during  the  cooling,  they  are  small. 

Crystallography,  treating  of  the  relations  of  the  geometric  forms  of 
crystals,  has  become  an  extended  branch  of  science,  only  the  fundamen- 
tal principles  and  chemical  applications  of  which  can  be  here  considered. 

Most  crystals  may  be  divided  by  one  or  more  imaginary  planes  into 
equal,  symmetrical  halves;  such  planes  are  called  planes  of  symmetry. 
A  normal  erected  upon  such  a  plane  and  prolonged  in  both  directions 
until  it  meets  opposite  parts  of  the  exterior  of  the  crystal,  at  equal  dis- 
tances from  the  plane  of  symmetry,  is  called  an  axis  of  symmetry.  When 
a  plane  of  symmetry  contains  two  or  more  equivalent  linear  directions 
passing  through  the  centre,  that  plane  is  the  principal  plane  of  symmetry, 
and  the  axis  of  symmetry  normal  to  this  plane  is  the  principal  axis. 

Upon  the  relations  of  these  imaginary  planes  and  axes  a  classification 
of  all  crystalline  forms  into  six  systems  has  been  based.  These  systems 
are  the  following: 

First. —  The  regular  or  cubic  system. — In  crystals  of  this  system  there 
are  three  equal  axes  crossing  each  other  at  right  angles.  The  simple  forms 
are  the  cube  and  its  derivatives,  the  octahedron,  tetrahedron,  and  rhombic 
dodecahedron.  The  crystals  expand  equally  in  all  directions  when  heated, 
and  are  not  doubly  refracting. 

Second. — The  pyramidal,  right  square  prismatic  or  tetragonal  system 


PHYSICAL    CHARACTERS    OF    CHEMICAL    INTEREST.  29^ 

contains  those  crystals  which  have  three  axes  placed  at  right  angles  to- 
each  other — two  being  equal  to  each  other,  and  the  third  either  longer  or 
shorter.  The  simple  forms  are  two  prisms,  in  one  of  which  the  equal 
axes  terminate  in  the  angles  of  the  principal  plane,  and  in  the  other  in 
its  sides;  and  two  octahedra,  differing  from  each  other  in  the  same  way 
as  the  prisms.  The  crystals  of  this  system  expand  equally  only  in  two- 
directions  when  heated;  they  have  but  one  axis  of  single  refraction,  and 
in  other  directions  refract  light  doubly. 

Third. — The  hexagonal  or  rhombohedral  system  includes  crystals  hav- 
ing four  axes,  three  of  which  are  of  equal  length,  cross  each  other  at  60°,. 
and  in  the  same  plane;  to  which  plane  the  fourth  axis,  longer  or  shorter 
than  the  others,  is  at  right  angles.  The  simple  forms  are  the  direct  dode- 
cahedron, composed  of  two  hexagonal  pyramids  base  to  base,  in  which 
the  equal  axes  terminate  in  the  angles  of  the  principal  plane;  the  inverse- 
dodecahedron,  which  differs  from  the  direct  in  that  the  axes  terminate  in 
the  sides  of  the  principal  plane;  the  rhombohedron;  and  the  six-sided 
prism.  The  crystals  expand  equally  in  two  directions  when  heated;  re- 
fract light  singly  through  the  principal  axis,  but  in  other  directions 
refract  it  doubly. 

Fourth. — The  rhombic,  right  rectangular  prismatic,  or  prismatic  sys- 
tem.— The  axes  of  crystals  of  this  system  are  three  in  number,  all  at  right 
angles  to  each  other,  and  differing  in  length.  They,  like  the  two  follow- 
ing systems,  have  no  true  principal  plane  or  axis.  The  simple  forms  are 
the  right  rhombic  octahedron  and  the  right  prism  with  a  rhombic  base. 

Fifth. — The  oblique  or  monosymmetric  system. — The  crystals  of  this 
system  have  three  axes,  two  of  which  cross  each  other  obliquely  and  at 
right  angles  to  the  third.  These  axes  may  be  all  of  unequal  length. 
The  simple  forms  are  the  oblique  octahedron  with  a  rhombic  base  and 
the  oblique  rhombic  prism. 

Sixth. — The  asymmetric,  anorthic,  or  doubly  oblique  system  contains 
crystals  having  three  axes  of  unequal  length,  crossing  each  other  at  an- 
gles not  right  angles. 

The  crystals  of  the  fourth,  fifth,  and  sixth  systems,  when  heated,  ex- 
pand equally  in  the  directions  of  their  three  axes;  they  refract  light 
doubly  except  in  two  axes. 

It  sometimes  happens  that  half  the  faces  of  a  simple  crystal  are  de- 
veloped in  the  formation  of  a  derivative  form  at  the  expense  of  the  other 
half,  which  are  entirely  wanting;  such  a  crystal  is  said  to  be  hemihedral" 
it  can  be  developed  only  in  a  system  having  a  principal  axis. 

ISOMORPHISM. — Although  the  number  of  simple  forms  of  crystals  is 
small,  the  number  of  their  modifications  is  great;  these  forms  differ  from 
each  other  in  the  values  of  the  axes  and  of  the  angles  of  the  crystals. 

It  has  been  observed  that  in  many  instances  two  or  more  substances 
crystallize  in  forms  absolutely  identical  which  each  other,  and,  in  most 
cases,  such  substances  resemble  each  other  in  their  chemical  constitution; 
they  are  said  to  be  isomorphous.  This  identity  of  crystalline  form  does  not 
depend  so  much  upon  the  nature  of  the  elements  themselves,  as  upon  the 
structure  of  the  molecule.  The  protoxide  and  peroxide  of  iron  do  not 
crystallize  in  the  same  form,  nor  can  they  be  substituted  for  each  other 
in  reactions  without  radically  altering  the  properties  of  the  resultant  com- 
pound. On  the  other  hand,  all  that  class  of  salts  known  as  alums  (see 
p.  383)  are  isomorphous;  not  only  are  their  crystals  identical  in  shape, 
but  a  crystal  of  one  alum,  placed  in  a  saturated  solution  of  another,  grows 
by  regular  deposition  of  the  second  upon  its  surface.  Other  alums  may- 


30  GENERAL    MEDICAL    CHEMISTRY. 

be  subsequently  added  to  the  crystal,  a  section  of  which  will  then  exhibit 
the  various  salts,  layer  upon  layer. 

DIMORPHISM. — Although  most  substances  crystallize,  if  at  all,  in  one 
simple  form  or  in  some  of  its  modifications,  a  few  bodies  are  capable  of 
assuming  two  crystalline  forms  belonging-to  different  systems;  such  are 
said  to  be  dimorphous.  Thus,  sulphur,  as  obtained  by  the  evaporation  of 
its  solution  in  carbon  disulphide,  forms  octahedra  belonging  to  the  fourth 
system;  when  obtained  by  cooling  melted  sulphur,  the  crystals  are  oblique 
prisms,  belonging  to  the  fifth  system.  Occasional  instances  of  trimor- 
phism,  of  the  formation  of  crystals  belonging  to  three  different  systems 
by  the  same  substance,  are  also  known. 

ALLOTROPY. — Dimorphism  apart,  a  few  substances  are  known  to  exist  in 
more  tkan  one  solid  form.  These  varieties  of  the  same  substance  exhibit 
different  physical  properties,  while  their  chemical  qualities  are  the  same 
in  kind.  Such  modifications  are  said  to  be  allotropic.  One  or  more  allo- 
tropic  modifications  of  a  substance  are  crystalline,  the  other  or  others 
amorphous  or  vitreous.  Sulphur,  for  example,  exists  not  only  in  two  di- 
morphous varieties  of  crystals,  but  also  in  a  third,  allotropic  form,  in  which 
it  is  flexible,  amorphous,  and  transparent.  Carbon  exists  in  three  allotro- 
pic forms  :  two  crystalline,  the  diamond  and  graphite  ;  the  third  amor- 
phous. 

In  passing  from  one  allotropic  modification  to  another,  a  substance 
absorbs  or  gives  out  heat. 

SPECIFIC  HEAT. — Equal  volumes  of  different  substances  at  the  same 
temperature  contain  different  amounts  of  heat.  If  two  equal'  volumes  of 
the  same  liquid  of  different  temperatures  be  mixed  together,  the  resulting1 
mixture  has  a  temperature  which  is  the  mean  between  the  temperatures 
of  the  original  volumes.  If  one  litre  of  water  at  4°  be  mixed  with  a  litre  at 
38°,  the  resulting  two  litres  will  have  a  temperature  of  21°.  Mixtures  of 
equal  volumes  of  different  substances  at  different  temperatures  do  not 
have  a  temperature,  which  is  the  mean  of  the  original  temperatures  of 
its  constituents.  A  litre  of  water  at  4°,  mixed  with  a  litre  of  mercury 
at  38°,  forms  a  mixture  whose  temperature  is  27°.  Mercury  and  water, 
therefor,  differ  from  each  other  in  their  capacity  for  heat.  The  same 
difference  exists  in  a  more  marked  degree  between  equal  weights  of  dis- 
similar bodies;  if  a  pound  of  water  at  4°  be  agitated  with  a  pound  of 
mercury  at  70°,  both  liquids  will  have  a  temperature  of  67°. 

The  amount  of  heat  required  to  raise  a  kilo  of  water  1°  in  tempera- 
ture is  a  definite  quantity.  The  specific  heat  of  any  substance  is  the 
amount  of  heat  required  to  raise  one  kilo  of  that  substance  1°  in  tempera- 
ture, expressed  in  terms  having  the  amount  of  heat  required  to  raise  a 
kilo  of  water  1°  as  unity. 

SPECTROSCOPY. — Light  in  passing  through  a  prism  is  not  only  refracted 
into  a  different  course,  but  is  also  decomposed  or  dispersed  into  different 
colors,  which  make  up  a  spectrum.  A  spectrum  is  one  of  three  kinds: 
1st,  continuous,  consisting  of  a  continuous  band  of  colors:  red,  orange, 
yellow,  green,  blue,  indigo,  and  violet.  Such  spectra  are  produced  by 
light  from  white-hot  solids  and  liquids,  from  gas-light,  candle-light,  lime- 
light, and  electric  light.  2d,  bright-line  spectra,  composed  of  bright 
lines  upon  a  dark  ground,  are  produced  by  glowing  vapors  and  gases. 
3d,  absorption  spectra  consist  of  continuous  spectra  crossed  by  dark  lines 
or  bands,  and  are  produced  by  light  which  gives  a  continuous  spectrum 
passing  through  a  solid,  liquid,  or  gas  capable  of  absorbing  rays  of  certain 
colors. 


PHYSICAL    CHARACTERS    OF    CHEMICAL    INTEREST.  31 

The  solar  spectrum  belongs  to  the  third  class.  Fraunhofer  was  the 
first  to  observe  that  the  spectrum  of  sunlight  was  not  continuous,  but  in- 
terrupted by  a  great  number  of  black  lines,  crossing  it  throughout  its 
length.  The  more  prominent  of  these  lines  he  designated  by  the  letters 
A,  B,  C,  D,  E,  F,  G,  H,  a,  and  b.  Most  of  these  lines  correspond  in  po- 
sition with  the  bright  lines  produced  by  the  incandescent  vapors  of  vari- 
ous elements. 

The  spectroscope  consists  of  four  essential  parts  :  1st,  the  slit,  a 
linear  opening  between  two  accurately  straight  and  parallel  knife-edges  ; 
2d,  the  collirnating  lens,  a  biconvex  lens  in  whose  principal  focus  the 
slit  is  placed,  and  whose  object  it  is  to  render  the  rays  from  the  slit 
parallel  before  they  enter  the  prism  ;  3d,  the  prism  of  dense  glass, 
and  usually  of  60°,  so  placed  that  its  refracting  edge  is  parallel  to  the  slit; 
4th,  an  observing  telescope,  so  arranged  as  to  receive  the  rays  as  they 
emerge  from  the  prism.  In  direct  "vision  spectroscopes  a  compound 
prism  is  used,  so  made  up  of  prisms  of  different  kinds  of  glass  that  the 
emerging  ray  is  in  the  same  straight  line  as  the  entering  ray. 

As  the  spectra  produced  by  different  substances  are  characterized  by 
the  positions  of  the  lines  or  bands,  some  means  of  fixing  their  location 
is  required.  The  usual  method  consists  in  determining  their  relation  to 
the  principal  Fraunhofer  lines.  As,  however,  the  relative  positions  of 
these  lines  vary  with  the  nature  of  the  substance  of  which  the  prism  is 
made,  although  their  position  with  regard  to  the  color  of  the  spectrum  is 
fixed,  no  two  of  the  arbitrary  scales  used  will  give  the  same  reading. 

The  most  satisfactory  method  of  stating  the  positions  of  lines  and 
bands  is  in  wave-lengths.  The  lengths  of  the  waves  of  rays  of  different 
degrees  of  refrangibility  have  been  carefully  determined,  the  unit  of 
measurement  being  the  tenth-metre,  of  which  1010  make  a  metre.  The 
wave-lengths,  =A,  of  the  principal  Fraunhofer  lines,  are: 

A ,    7604.00     D 5892.12     G 4307.25 

B 6867.00     E 5269.13     H, 3968.01 

C 6562.01     F 4860.72     H2 3933.00 

a 7185.0     b 5172.0 

The  scale  of  wave-lengths  can  easily  be  used  with  any  spectroscope 
having  an  arbitrary  scale,  with  the  aid  of  a  curve  constructed  by  interpo- 
lation. To  construct  such  a  curve  paper  is  used  which  is  ruled  into  square 
inches  and  tenths.  The  ordinates  are  marked  with  a  scale  of  wave- 
lengths and  the  abscisses  with  the  arbitrary  scale  of  the  instrument.  The 
position  of  each  principal  Fraunhofer  line  is  then  carefully  determined  in 
terms  of  the  arbitrary  scale,  and  marked  upon  the.  paper  with  a  x  at  the 
point  where  the  line  of  its  wave-length  and  that  of  its  position  in  the  ar- 
bitrary scale  cross  each  other.  Through  these  x  a  curve  is  then  drawn 
as  regularly  as  possible.  In  noting  the  position  of  an  absorption-band  the 
position  of  its  centre  in  the  arbitrary  scale  is  observed,  and  its  value  in 
wave-lengths  obtained  from  the  curve,  which,  of  course,  can  only  be 
used  with  the  scale  and  prism  for  which  it  has  been  made. 

POLARIMETRY. — A  ray  of  light  passing  from  one  medium  into  another 
of  different  density,  at  an  angle  other  than  90°  to  the  plane  of  sepa- 
ration of  the  two  media,  is  deflected  from  its  course,  or  refracted.  Cer- 
tain substances  have  the  power,  not  only  of  deflecting  a  ray  falling 
upon  them  in  certain  directions,  but  also  of  dividing  it  into  two  rays, 
which  are  peculiarly  modified.  The  splitting  of  the  ray  is  termed  double 


32  GENERAL    MEDICAL    CHEMISTRY. 

refraction,  and  the  altered  rays  are  said  to  be  polarized,  When  a  ray  of 
such  polarized  light  meets  a  mirror  held  at  a  certain  angle,  or  a  crystal  of 
Iceland  spar  peculiarly  cut  (a  Nichols'  prism),  also  at  a  certain  angle,  it 
is  extinguished.  The  crystal  which  produces  the  polarization  is  called 
the  polarizer,  and  that  which  produces  th€r  extinction  the  analyzer. 

If,  when  the  polarizer  and  analyzer  are  so  adjusted  as  to  extinguish  a 
~ay  passing  through  the  former,  certain  substances  are  brought  between 
chem,  light  again  passes  through  the  analyzer;  and  in  order  again  to  pro- 
duce extinction,  the  analyzer  must  be  rotated  upon  the  axis  of  the  ray  to  the 
right  or  to  the  left.  Substances  capable  of  thus  influencing  polarized  light 
are  said  to  be  optically  active,.  If,  to  produce  extinction,  the  analyzer  is 
turned  in  the  direction  of  the  hands  of  a  watch,  the  substance  is  said  to 
be  dextrogyrous  •  if  in  the  opposite  direction,  Icevogyrous. 

The  distance  through  which  the  analyzer  must  be  turned  depends  upon 
the  peculiar  power  of  the  optically  active  substance,  the  length  of  the 
column  interposed,  the  concentration  if  in  solution,  and  the  wave-length 
of  the  original  ray  of  light.  The  specific  rotary  power  of  a  substance  is 
the  rotation  produced,  in  degrees  and  tenths,  by  one  gram  of  the  sub- 
stance dissolved  in  one  cubic  centimetre  of  a  non-active  solvent,  and  ex- 
amined in  a  column  one  decimetre  long.  The  specific  rotary  power  is  de- 
termined by  dissolving  a  known  weight  of  the  substance  in  a  given  volume 
of  solvent,  and  observing  the  angle  of  rotation  produced  by  a  column  of 
given  length.  Then  let  jt>=  weight  in  grams  of  the  substance  contained 
in  1  c.c.  of  solution;  I  the  length  of  the  column  in  decimetres;  a  the  an- 
gle of  rotation  observed;  and  [a]  the  specific  rotary  power  sought,  we 
have 


pi 

In  most  instruments  monochromatic  light,  corresponding  to  the  D  line  of 
the  solar  spectrum,  is  used,  and  the  specific  rotary  power  for  that  ray  is 
expressed  by  the  sign  [a]D.  The  fact  that  the  rotation  is  right-handed  is 
expressed  by  the  sign  -J-,  and  that  it  is  left-handed  by  the  sign  —  . 

It  will  be  seen  from  the  above  formula  that,  knowing  the  value  of  [«]D 
for  any  given  substance,  we  can  determine  the  weight  of  that  substance 
in  a  solution  by  the  formula 

a 

fft  --—  —  _  , 


2. 

SPECIAL   CHEMISTRY. 


CLASS  I. 

TYPICAL   ELEMENTS. 

HYDROGEN H 1 

OXYGEN O 16 

ALTHOUGH,  in  a  strict  sense,  hydrogen  is  regarded  by  most  chemists  as 
the  one  and  only  type-element — that  whose  atom  is  the  unit  of  atomic 
and  molecular  weights — the  important  part  which  oxygen  plays  in  the 
formation  of  those  compounds  whose  nature  forms  the  basis  of  our  clas- 
sification, its  acid-forming  power  in  organic  compounds,  and  the  differ- 
ences existing  between  its  properties  and  those  of  the  elements  of  the 
sulphur  group,  with  which  it  is  usually  classed,  warrant  us  in  separating 
it  from  the  other  elements  and  elevating  it  to  the  position  it  here  occu- 
pies. 

HYDROGEN. 

H..  ..1 


Hydrogen  exists  uncombined  in  the  gases  from  the  fumaroles  of  Ice- 
land and  Tuscany;  in  combination  very  abundantly  in  water,  in  many 
organic  substances,  and  in  ammoniacal  compounds. 

Hydrogen  is  liberated  from  its  compounds: 

First.  —  By   the  decomposition  of  acidulated  water  by  the  galvanic 
current,  when  it  is  given  off  from  the  negative  pole.     This  method  is  re 
sorted  to  when  chemically  pure  hydrogen  is  required. 

Second.  —  By  the  decomposition  of  water  by  the  chemical  action  of 
certain  metals.  This  takes  place  either  at  ordinary  temperatures,  as  in 
the  case  of  sodium  — 


or  at  a  red  heat,  as  in  the  case  of  iron  — 


34  GENERAL    MEDICAL    CHEMISTKY. 

Third. — By  the  decomposing  action  exerted  by  certain  metals,  such 
as  zinc,  upon  the  mineral  acids  in  the  presence  of  water — 

Zn  +  SO4Ha  +  xH2O = SO4Zn  +  Ha + xHaO. 

What  part  the  water  plays  in  the  reaction  is  still  a  subject  of  discus- 
sion ;  it  is  probable  that  its  action  is  rather  physical  than  chemical. 
Chemically  pure  zinc,  or  zinc  whose  surface  has  been  coated  with  an 
alloy  of  zinc  and  mercury,  does  not  decompose  the  acid  unless  it  forms 
part  of  a  galvanic  battery  whose  circuit  is  closed.  Th*s  zincs  of  galvanic 
batteries  are  therefor  coated  with  the  alloy  mentioned — are  amalgam- 
ated— to  prevent  waste  of  zinc  and  acid. 

This  method  is  the  one  resorted  to  for  obtaining  hydrogen  in  the 
laboratory  ;  the  gas  so  obtained  is,  however,  contaminated  with  small 
quantities  of  other  gases,  hydrogen  phosphide,  sulphide,  and  arsenide. 

At  ordinary  temperatures  and  pressure,  and  when  pure,  it  is  a  colorless, 
odorless,  tasteless  gas,  fourteen  and  one-half  times  lighter  than  air,  being 
the  lightest  known  substance.  One  litre  at  0°  and  760  mm.  barometric  pres- 
sure weighs  0.0896  gram,  a  quantity  which  forms  an  important  unit  of 
weight,  called  by  Hofmann  a  crith  (KpiOr)  =  a  barley-corn).  It  is  almost  in- 
soluble in  water  and  in  alcohol.  It  is  a  better  conductor  of  heat  and  elec- 
tricity than  is  any  other  gas.  It  is  the  most  diffusible  of  gases,  in  obedi- 
ence to  the  law  that  the  diffusion  volume  of  a  gas  is  in  inverse  proportion 
to  the  square  root  of  its  density.  The  rapidity  with  which  its  diffusion 
takes  place  renders  the  use  of  hydrogen,  which  has  been  kept  for  even  a 
comparatively  short  time  in  metallic  gasometers,  dangerous  from  the 
formation  of  explosive  mixtures  of  air  and  hydrogen  within.  India-rub- 
ber gas-bags  are  more  dangerous  than  metallic  gasometers. 

Hydrogen  was  formerly  supposed  to  be  a  permanent  gas,  i.  e.,  not 
capable  of  reduction  to  the  liquid  or  solid  state.  Recently,  however, 
Cailletet,  of  Paris,  obtained  it  in  the  form  of  a  visible  cloud  ;  and  Pictet, 
of  Geneva,  with  a  pressure  of  650  atmospheres  and  a  temperature  of 
— 140°,  succeeded  in  reducing  it  to  a  steel-blue  liquid. 

Under  ordinary  conditions  hydrogen  exhibits  no  great  tendency  to 
unite  with  other  elements,  chlorine  being  the  only  one  with  which  it  will 
unite  at  ordinary  temperatures,  and  that  only  under  the  influence  of 
light.  At  higher  temperatures  it  unites  with  oxygen. 

Mixtures  of  hydrogen  and  oxygen  remain  such  indefinitely  at  ordinary 
temperatures,  but  if  heated  sufficiently  even  at  a  single  point,  as  by  the 
passage  of  an  electric  spark,  a  sudden  and  complete  union  takes  place 
throughout  the  mass  (if  the  proportions  be  H2  to  Ol),  attended  by  a  vio- 
lent explosion,  due  to  the  formation  of  vapor  of  water  and  its  sudden  ex- 
pansion under  the  influence  of  the  intense  heat  produced  by  the  union. 
Hydrogen  has  so  marked  a  tendency  to  unite  with  oxygen  at  high  tem- 
peratures that  many  compounds  containing  oxygen  give  up  that  element 
when  heated  in  an  atmosphere  of  hydrogen  : 

CuO    +     H2    =    Cu    +    H,O. 

Cupric  oxide.      Hydrogen.     Copper.          Water. 

This  removal  of  oxygen  from  a  compound  is  called  a  reduction  or  de- 
oxidation,  and  it  is  by  such  a  process  that  the  reduced  iron,  or  iron  by 
hydrogen  of  pharmacy,  is  prepared. 

At  the  instant  that  hydrogen  is  liberated  from  its  compounds  it  has  a 
deoxidizing  power  similar  to  that  which  ordinary  hydrogen  possesses  only 


OXYGEN.  35 

at  elevated  temperatures.  The  greater  energy  of  hydrogen,  and  of  other 
elements  as  well,  in  this  nascent  state,  may  be  thus  explained:  free  hydro- 
gen exists  in  the  form  of  molecules,  each  one  of  which  is  composed  of  two 
atoms.  At  the  instant  of  its  liberation  from  a  compound,  on  the  other 
hand,  it  is  in  the  form  of  individual  atoms,  and  that  portion  of  force  re- 
quired to  split  up  the  molecule  into  atoms,  necessary  when  free  hydrogen 
enters  into  reaction,  is  not  required  when  the  gas  is  in  the  nascent  state, 
and  consequently  a  less  addition  of  force  in  the  shape  of  heat  is  required 
to  bring  about  the  reaction. 

Hydrogen  burns  in  air  with  a  pale  but  hot  flame,  the  product  of  the 
combustion  being  water.  It  does  not  maintain  combustion  or  respiration;  a 
lighted  taper  is  extinguished  when  immersed  in  an  atmosphere  of  hydro- 
gen, and  under  like  conditions  an  animal  dies — not  from  any  poisonous 
action  of  the  gas,  but  from  its  inability  to  maintain  the  processes  of  res- 
piration. 

In  its  physical  and  chemical  properties,  this  element  more  closely  re- 
sembles those  usually  ranked  as  metals  than  it  does  those  forming  the  class 
of  metalloids,  among  which  it  is  usually  placed;  its  conducting  power,  its 
appearance  in  the  liquid  form,  as  well  as  its  relation  to  the  acids,  which 
may  be  considered  as  salts  of  hydrogen,  tend  to  separate  it  from  the 
metalloids. 

Hydrogen  is  constantly  found  in  small  quantity  in  the  gases  exhaled 
from  the  lungs,  as  well  as  in  those  contained  in  the  stomach  and  intestines. 


OXYGEN. 
O 16 

Oxygen  is  the  most  abundant  of  the  elements,  and  exists  uncombined 
in  atmospheric  air,  of  which  it  forms  21  per  cent.  It  also  enters  into  the 
composition  of  a  vast  number  of  compound  substances,  mineral,  vege- 
table, and  animal. 

Although  existing  in  air,  and  only  mixed  with  nitrogen  and  small  quan- 
tities of  other  gases,  no  process  has  yet  been  devised  which  can  be  advan- 
tageously used  for  obtaining  oxygen  from  this  source  directly.  Resource 
is  always  had  to  the  decomposition  of  some  substance  rich  in  oxygen. 

First. — By  heating  mercuric  oxide  (the  red  oxide)  it  is  decomposed 
into  mercury  and  oxygen: 

2HgO=2Hg+Oa. 

This  process  is  only  of  historical  interest,  as  being  the  one  by  which 
Priestley  first  obtained  oxygen  in  1774. 

Second. — By  heating  manganese  dioxide  (black  oxide  of  manganese)  to 
redness  in  an  iron  or  clay  retort: 

3MnO3=Mn304+02. 

The  yield  according  to  this  equation  should  be  85  litres  of  oxygen 
from  1  kilo  of  the  oxide;  but,  owing  to  impurities,  the  amount  is  much  less 
and  the  gas  is  impure. 

Third. — By  heating  manganese  dioxide  with  sulphuric  acid  in  a  glass 
flask: 


36  GENERAL    MEDICAL    CHEMISTRY. 

The  theoretical  yield  is  128  litres  of  gas  from  each  kilo  of  oxide. 
Fourth. — The  best  method,  and  that  generally  used,  is  by  the  decom- 
position of  potassium  chlorate  by  heat: 

2ClO3K=2KQl-f3O2. 

The  chlorate  yields  up  all  of  its  oxygen  to  the  amount  of  272.6  litres 
per  kilo  of  chlorate. 

The  evolution  of  gas  takes  place  at  a  lower  temperature  and  much 
more  quietly  if  the  chlorate  be  mixed  with  one  to  two  parts  by  weight  of  man- 
ganese dioxide.  At  the  end  of  the  operation  the  manganese  dioxide  re- 
mains apparently  unaltered,  and  it  is  probable  that  during  the  action  it 
goes  through  a  series  of  oscillating  oxidations  and  deoxidations,  which 
take  place  at  a  lower  temperature  than  that  required  for  the  decomposition 
of  the  chlorate  alone. 

Methods  have  been  suggested  by  Tessie  du  Motay,  Boussingault,  and 
Mallet,  for  extracting  oxygen  from  the  air,  and  attempts  have  been  made 
to  utilize  these  processes  in  the  arts;  but  the  chlorate  process  is  still  in 
general  use,  on  account  of  its  comparative  cheapness  and  the  purity  of  the 
product. 

Oxygen  is  a  colorless,  odorless,  tasteless  gas;  liquefies  under  the  com- 
bined influence  of  a  pressure  of  300  atmospheres  and  a  temperature  of 
—140°  (Pictet).  The  specific  gravity  of  the  gas  is  1.10563  A,*  or  15.95 
H,f  and  that  of  the  liquid  0.9787  (Pictet);  1  litre  of  the  gas  at  0°  C. 
and  760  mm.  weighs  1.437  gram.  It  is  very  sparingly  soluble  in  water, 
somewhat  more  soluble  in  absolute  alcohol. 

Oxygen  is  characterized,  chemically,  by  the  strong  tendency  which 
it  exhibits  to  enter  into  combination  with  other  elements,  only  one  of 
which  is  known,  i.  e.,  fluorine,  that  does  not  form  an  oxygenated  com- 
pound. With  most  elements  it  is  capable  of  uniting  directly,  especially 
at  elevated  temperatures.  In  many  instances  this  union  is  attended  by  the 
appearance  of  light,  and  always  by  the  extrication  of  heat.  The  lumi- 
nous union  of  oxygen  with  another  element  constitutes  the  familiar  phe- 
nomenon of  combustion,  and  is  the  principal  source  from  which  we  obtain 
heat  and  light.  A  body  is  said  to  be  combustible  when  it  is  capable  of 
so  energetically  combining  with  oxygen  as  to  liberate  light  as  well  as 
heat.  Certain  gases  are  said  to  be  supporters  of  combustion,  because 
combustible  substances  will  unite  with  them  or  with  some  of  their  con- 
stituents, the  union  being  attended  with  the  appearance  of  heat  and 
light.  The  distinction  between  combustible  substances  and  supporters 
of  combustion  is,  however,  one  of  mere  convenience;  the  action  taking 
place  between  the  two  substances,  one  is  as  much  a  party  to  it  as  the 
other. 

A  jet  of  air  burns  in  an  atmosphere  of  coal-gas  as  readily,  and  with 
the  same  luminous  flame  which  is  observed  when  a  jet  of  coal-gas  'is 
caused  to  burn  in  air. 

Oxidations,  and  indeed,  most  chemical  unions,  are  attended  with  a 
liberation  of  heat;  and  in  some  instances,  as  when  powdered  antimony  is 
thrown  into  an  atmosphere  of  chlorine,  light  is  also  observed  without  the 
occurrence  of  any  oxidation. 

The  process  of  respiration  is  very  similar  to  combustion,  and  as  oxy- 
gen gas  is  the  best  supporter  of  combustion,  so,  in  the  diluted  form  in 

*  Air  unity.  f  Hydrogen -unity. 


COMPOUNDS  OF  HYDROGEN  AND  OXYGEN.         37 

which   it   exists  in  atmospheric  air,  it  is  not  only  the  best,  but  the  only 
supporter  of  animal  respiration. 


Ozone. 

Air  through  which  discharges  of  static  electricity  have  passed  as- 
sumes a  peculiar  odor,  resembling  somewhat  that  of  sulphur;  the  same 
odor  is  perceived  in  the  oxygen  obtained  by  the  decomposition  of  water 
if  the  electrodes  be  of  platinum  or  gold.  This  odor  is  due  to  the  conver- 
sion of  a  part  of  the  oxygen  into  an  allotropic  modification  called  ozone. 

Ozone  has  not  been  obtained  free  from  oxygen;  indeed,  the  highest 
degree  of  concentration  which  has  been  reached  does  not  exceed  one  per 
<jent.  of  ozone.  Thus  diluted,  ozone  is  produced:  1st,  by  the  decom- 
position of  water  by  the  battery;  2d,  by  the  slow  oxidation  of  phos- 
phorus in  damp  air;  3d,  by  the  action  of  concentrated  sulphuric  acid 
upon  barium  dioxide;  4th,  by  the  passage  of  electric  discharges  through 
air  or  oxygen.  It  is  by  the  last  method  that  ozonized  oxygen  is  usu- 
ally obtained  artificially,  and  that  the  traces  of  ozone  existing  in  the 
atmosphere  are  produced. 

Ozone  is  condensed  oxygen,  as  is  shown,  by  the  fact  that  the  latter 
gas  contracts  when  ozonized.  When  heated  to  100°  it  begins  to  revert  to 
its  primitive  form  of  oxygen,  a  change  which  is  complete  at  237°.  It  is 
a  powerful  oxidizing  agent;  it  converts  iodides  into  iodates;  it  is  de- 
stroyed by  contact  with  rubber,  cork,  and  other  organic  materials,  which 
it  oxidizes;  it  decolorizes  organic  pigments. 

The  presence  of  ozone  in  air  is  demonstrated  by  its  action  upon  a 
paper  impregnated  with  a  mixture  of  starch  and  potassium  iodide,  which 
turns  blue  on  contact  with  ozone.  To  exclude  other  gases  capable  of 
bluing  such  paper,  a  faintly  red  litmus  paper,  impregnated  with  potas- 
sium iodide  to  half  its  extent,  is  also  used;  if  the  bluing  of  the  starch 
paper  be  due  to  ozone,  the  litmus  paper  is  also  blued,  and  the  action  upon 
either  paper  does  not  take  place  after  the  ozonized  air  has  been  heated 
to  260°. 

When  inhaled,  air  containing  0.07  gram  of  ozone  per  litre  causes  in- 
tense coryza  and  haemoptysis.  Its  presence  in  atmospheric  air  has  been 
considered  by  some  as  favoring,  and  by  others  as  preventive  of,  conta- 
gious diseases  ;  certain  it  is  that,  by  its  oxidizing  action,  ozone  is  fatal  to 
the  lower  forms  of  animal  and  vegetable  life. 


Compounds  of  Hydrogen  and  Oxygen. 

Two  of  these  are  known: 

First. — Hydrogen  oxide,  or  water. 

Second. — Hydrogen  peroxide,  or  oxygenated  water. 

WATEK— HO. 


Occurrence. — Water  exists,  widely  disseminated  and  in  large  quantities, 
in  the  three  kingdoms  of  nature,  in  the  three  forms  of  solid,  liquid,  and 
gas. 

In  unorganized  nature,  water  occurs  in  the  gaseous  form  in  atmos- 
pheric air  (see  p.  96),  and  in  the  vapors  discharged  from  the  earth  in 
volcanic  regions.  In  the  liquid  form  it  exists  very  abundantly,  hold- 


38  GENERAL    MEDICAL    CHEMISTRY. 

ing  in  solution  solid  and  gaseous  matter  in  varying  quantities.  In  the 
solid  form,  as  ice,  at  temperatures  below  0°  C.,  and  also  in  the  form  of 
water  of  crystallization,  by  which  is  understood  a  certain  definite  quan- 
tity of  water  taken  up  by  many  substances  when  they  assume  the  crys- 
talline form.  This  water  is  no*  in  the  liquid  form  at  ordinary  tempera- 
tures, nor  yet  in  the  form  of  ice,  but  combined  with  the  solid  matter  of 
the  crystal.  Although  the  chemical  nature  of  the  substance  is  not  modi- 
fied by  the  presence  or  absence  of  water  of  crystallization,  its  presence  is 
necessary  to  the  maintenance  of  the  peculiar  shape  of  the  crystal.  The 
tenacity  with  which  water  of  crystallization  is  held  in  combination  varies 
in  different  substances;  in  some  the  union  is  so  loose  that  on  exposure 
to  air  the  crystal  loses  its  water  and  falls  to  a  shapeless  powder;  it  is  then 
said  to  effloresce.  Other  crystals,  which  are  said  to  be  permanent  in  air, 
only  lose  their  water  of  crystallization  if  heated;  they  then  melt,  and 
part  or  all  the  water  is  driven  off,  leaving  a  shapeless  mass,  which  is 
capable  of  crystallization  only  when  the  proper  amount  of  water  is  again 
taken  up. 

In  the  organized  world,  water  forms  a  constituent  part  of  every  fluid 
and  tissue  (see  p.  67). 

Formation.  —  Water  is  produced  in  a  great  number  of  chemical  re- 
actions. 

First.  —  Most  simply  by  the  direct  union  of  its  constituent  gases, 
brought  about  by  elevation  of  temperature: 


In  obedience  to  Avogadro's  law,  the  volume  of  water-gas  formed  is  to 
the  volume  of  the^  mixture  before  union  as  2  :  3,  provided  the  mixture 
originally  contained  two  volumes  of  hydrogen  to  one  volume  of  oxygen. 

Second.  —  Whenever  hydrogen,  or  a  substance  containing  hydrogen,  is 
burned  in  air  or  oxygen. 

Third.  —  When  an  organic  substance  containing  hydrogen  is  heated  to 
redness-  in  the  presence  of  cupric  oxide,  or  of  other  substances  capable  of 
yielding  oxygen  — 

C2H6O  +  6CuO  =  6Cu  +  2CO2  +  3H2O, 

Alcohol.         Cupric     Copper.     Carbon        Water. 
oxide.  dioxide. 

a  reaction  which  is  utilized   for   the    determination  of   the   amount  of 
hydrogen  contained  in  organic  substances. 

Fourth.  —  When  an  acid  and  a  hydrate  react  upon  each  other  to  form 
a  salt  : 


SO4H2  +  2KHO  =  SO4KQ 

Sulphuric     Potassium    Potassium       Water. 
acid.  hydrate.       sulphate. 

Fifth.  —  In  the  reduction  of  metallic  oxides  by  hydrogen  : 
CuO  +  Ha  =  Cu   +    H20. 

Cupric     Hydrogen.     Copper.          Water. 
oxide. 

Sixth.  —  In  the  reduction  and  oxidation  of  a  number  of  organic  sub- 
stances. 


COMPOFNDS  OF  HYDROGEN  AND  OXYGEN.         39 

Pure  water  may  be  obtained  either  by  the  union  of  its  elements  or 
by  the  separation  of  naturally  occurring  water  from  the  solid  and  gaseous 
substances  which  it  holds  in  solution  and  in  suspension.  The  purification 
of  natural  water,  effected  by  the  processes  of  filtration  and  distillation,  is 
the  method  resorted  to  in  all  cases.  To  obtain  water  sufficiently  pure 
for  chemical  purposes,  it  is  boiled  in  a  vessel  of  tinned  copper,  called  a 
still,  and  the  vapor  is  directed  through  a  tube,  around  which  cold  water 
is  made  to  circulate,  and  in  which  the  vapor  is  condensed  to  the  liquid 
form.  The  condensing  tube  is  usually  of  block-tin,  or,  preferably,  of  glass. 
The  first  10  per  cent,  of  condensed  water  is  rejected,  as  it  contains  air, 
carbon  dioxide,  ammonia,  and  many  volatile  substances  which  the  water 
may  have  held  in  solution.  The  following  70  per  cent,  of  the  original 
volume  is  collected  for  use,  the  distillation  being  stopped  while  20  per 
cent,  of  the  original  water  remains  in  the  still. 

Distilled  water  so  obtained  should  be  perfectly  clear,  colorless,  odor- 
less, and  tasteless,  and  should  leave  no  residue  when  a  small  quantity  is 
evaporated  upon  platinum  foil.  Although  ordinary  distilled  water  is 
sufficiently  pure  for  most  chemical  purposes,  it  is  not  absolutely  free 
from  impurity,  and  when  evaporated  in  a  platinum  basin  it  leaves  more 
or  less  residue.  To  obtain  a  chemically  pure  water  is  a  matter  of  some 
difficulty.  Distilled  water  should  be  used  in  the  preparation  of  all  aque- 
ous solutions  intended  for  use  in  chemical  manipulations. 

Physical  properties. — At  temperatures  below  0°  C.,  with  a  barometric 
pressure  of  760  mm.,  water  assumes  the  solid  form  ;  between  0°  and  100° 
it  is  liquid  ;  and  at  temperatures  above  100°,  the  pressure  remaining  the 
same,  it  is  gaseous.  The  freezing  and  boiling  points  are  modified  by  the 
barometric  pressure,  and  by  the  presence  of  solid  matter  in  solution  in 
water.  The  freezing-point  is,  under  ordinary  conditions,  at  0°  of  the 
Centigrade  scale,  and  at  32°  of  the  Fahrenheit.  Under  certain  conditions, 
as  when  enclosed  in  capillary  tubes  and  at  complete  rest,  it  may  be  cooled 
as  far  as  — 15°  C.  without  solidifying.  If  water  so  cooled  be  agitated,  it 
solidifies  instantly,  and  the  temperature  suddenly  rises  to  0°. 

In  solidifying,  water  is  rather  suddenly  expanded,  and  this  expansion 
takes  place  with  great  force;  for  this  reason  ice  is  lighter  than  water  at 
any  temperature  below  8.5°,  and  consequently  floats.  Water  is  at  its 
densest  at  4°  C.  The  solidification  of  water  is  a  crystallization;  the  form 
of  the  crystals,  which  belong  to  the  hexagonal  system,  may  be  readily 
observed  in  snow,  or  even,  under  suitable  conditions,  in  ice,  which  is  com- 
posed of  closely  applied  crystals. 

The  boiling-point  is  subject  to  much  greater  variations  than  the  freez- 
ing-point; it  falls,  with  diminutions  of  pressure,  to  the  extent  of  about 
1°  C.  for  each  fall  of  26  mm.  of  pressure.  Conversely,  as  the  pressure  is 
increased  the  boiling-point  rises,  attaining  200°  with  a  pressure  of  be- 
tween fifteen  and  sixteen  atmospheres.  Advantage  is  taken  of  the  fall 
of  the  boiling-point  with  diminished  pressure  to  measure  the  altitude  of 
mountains,  upon  the  tops  of  some  of  the  higher  of  which  boiling  water 
is  not  hot  enough  to  be  of  service  in  culinary  operations.  The  increased 
temperature  which  may  be  imparted  to  liquid  water  under  pressure  is 
utilized  in  many  processes  in  the  laboratory  and  in  the  arts,  for  effecting 
solutions  and  chemical  actions  which  do  not  take  place  at  lower  temper- 
atures. The  boiling-point  of  water  holding  solid  matter  in  solution  is 
higher  than  that  of  pure  water,  the  degree  of  increase  depending  upon 
the  amount  and  nature  of  the  substance  dissolved.  On  the  other  hand, 
mixtures  of  water  with  liquids  of  lower  boiling-point  boil  at  tempera- 


40  GENERAL    MEDICAL    CHEMISTRY. 

tures  less  than  100°.  Although  the  conversion  of  water  into  water-gas 
takes  place  most  actively  at  100°,  water  arid  ice  evaporate  at  all  tem- 
peratures. 

One  of  the  most  important  physical  properties  of  water  is  its  high 
rank  as  a  solvent,  there  being  comparatively  few  substances,  solid,  liquid, 
or  gaseous,  which  are  absolutely  insoluble  in  it.  The  solution  of  a  sub- 
stance in  water  may  take  place  in  two  very  different  ways.  The  action 
may  be  partly  chemical,  as  when  barium  oxide  is  dissolved  in  water,  com- 
bination of  the  two  substances  taking  place  with  formation  of  barium 
hydrate — 

BaO+H2O=BaH3Oa, 

which  is  subsequently  dissolved.  In  solutions  of  this  kind,  as  in  other 
instances  where  chemical  union  takes  place,  the  action  is  accompanied  by 
an  increase  of  temperature.  In  true  simple  solutions,  on  the  other  hand, 
as  when  common  salt  is  dissolved  in  water,  there  is  no  chemical  action; 
no  increase,  but,  on  the  contrary,  a  diminution  of  temperature. 

The  quantity  of  a  substance  which  a  given  volume  of  water  is  capable 
of  dissolving  depends  upon  the  nature  of  the  substance,  the  temperature, 
the  presence  or  absence  of  other  substances  already  in  solution,  and  the  pres- 
ence or  absence  of  another  solvent.  Some  substances  are  much  more  soluble 
in  water  than  others;  barium  sulphate  is  insoluble  in  water,  while  calcium 
chloride  has  such  an  avidity  for  the  solvent  that,  when  exposed  to  the  air,  it 
quickly  absorbs  sufficient  water  therefrom  to  form  a  solution.  That  pas- 
sage of  a  solid  into  solution  in  absorbed  water  is  known  as  deliquescence. 
As  a  rule,  the  power  of  water  to  dissolve  solids  increases  with  the  tem- 
perature, while  the  solubility  of  gases  in  water  is  greater  at  low  than  at 
high  temperatures.  The  quantity  of  any  substance  which  a  given  volume 
of  water  will  dissolve  at  a  given  temperature  is  definite;  and  when  this 
quantity  has  been  dissolved,  the  solution  is  said  to  be  saturated;  it  is 
only  so  for  that  degree  of  temperature  at  which  it  has  been  made.  Sat- 
urated solutions  of  solids,  as  a  rule,  can  be  made  to  dissolve  further  quan- 
tities by  elevation  of  temperature,  or  to  deposit  that  which  they  already 
hold  by  cooling.  Saturated  solutions  of  gases  are  modified  by  variations 
of  temperature  in  the  opposite  way.  In  the  cases  of  certain  salts,  solu- 
tions saturated  at  high  temperatures  may  be  cooled  without  depositing 
any  of  the  salt;  they  thus  become  at  lower  temperatures  supersaturated 
solutions;  containing  more  of  the  salt  than  they  could  be  made  to  dis- 
solve at  the  temperature  to  which  they  have  been  cooled.  A  saturated 
solution  of  one  substance  in  water  is  often  capable  of  dissolving  consid- 
erable quantities  of  another  substance,  and  of  then  becoming  capable  of 
taking  up  a  further  quantity  of  the  first  substance.  The  power  of  water 
to  dissolve  gases  increases  with  increased  pressure.  Fats,  resins,  and,  in 
general,  organic  substances  containing  a  large  number  of  carbon  atoms, 
are  insoluble  in  water. 

Vapor  of  water  is  colorless,  transparent,  invisible  (the  white  cloud, 
usually  called  steam,  is  produced  by  the  condensation  of  vapor  of  water 
into  minute  liquid  drops);  its  specific  gravity  is  0.6234A=1  or  18 — H=2. 
A  litre  of  vapor  of  water  weighs  (reduced  to  0°  and  760  mm.)  0.8064,  or 
nine  times  as  much  as  an  equal  volume  of  hydrogen. 

The  latent  heat  of  vaporization  of  water  is  536.5  ;  that  is,  as  much 
heat  is  required  to  vaporize  1  kilo  of  water  at  100°  as  would  raise  536.5 
kilos  1°  C.  in  temperature.  In  passing  from  the  liquid  to  the  gaseous 
form,  water  expands  1,696  times  in  volume. 


COMPOUNDS  OF  HYDKOGEN  AND  OXYGEN.         41 

Chemical  properties — Decompositions. — First. — By  passing  the  cur- 
rent of  a  galvanic  battery  through  acidulated  water,  two  volumes  of  hy- 
drogen are  given  off  at  the  zinc  or  negative  pole,  and  one  volume  of 
oxygen  at  the  platinum  or  positive  pole. 

Second. — By  passing  vapor  of  water  through  a  platinum  tube  heated 
to  whiteness,  or  through  a  porous  porcelain  tube  heated  to  about  1,100° 
(Deville). 

Third. — By  acting  upon  water  at  low  temperatures  with  the  alkaline 
metals,  hydrogen  is  given  off,  and  a  hydrate  of  the  metal  remains  in  solu- 
tion in  the  excess  of  water: 

2H2O  +  2K  =  2KHO  +  H2. 

Water.        Potassium.      Potassium        Hydrogen, 
hydrate. 

Fourth. — By  passing  vapor  of  water  over  iron  heated  to  redness,  an 
oxide  of  the  metal  is  formed  and  hydrogen  liberated  (see  p.  33). 

Other  reactions. — First. — Water  combines  with  many  metallic  oxides  to 
form  compounds  known  as  hydrates,  which  may  be  considered  as  molecules 
of  water  in  which  one-half  the  hydrogen  has  been  replaced  by  an  equivalent 
quantity  of  the  metal.  When  the  metal  is  univalent,  the  action  takes 
place  between  single  molecules  of  oxide  and  water,  with  the  formation  of 
two  molecules  of  hydrate;  or,  mother  words,  the  hydrate  is  formed  by  the 
substitution  of  an  atom  of  metal  for  one  atom  of  hydrogen  in  a  single 
molecule  of  water: 

K3O    +  H3O    =  2KHO; 
or 


Potassium         Water.  Potassium 

oxide.  hydrate. 

When  the  metal  is  divalent,  thev  action  still  takes  place  between  single 
molecules  of  water  and  oxide,  but  with  the  formation  of  a  single  molecule 
of  hydrate;  or,  in  other  words,  the  hydrate  is  formed  by  the  substitution 
of  an  atom  of  the  divalent  metal  for  a  double  atom  of  hydrogen  in  a 
double  molecule  of  water: 

CaO  +    H2O     = 
or, 

Ca)    ,    H)  n_Ca 

Or   ~T~    TJ    (    ^-'   —  TT 
j  ±1   J  ±12 

Calcium        Water.  Calcium 

oxide.  hydrate. 

Second. — Water  combines  also  with  the  oxides  of  those  elements  usu- 
ally classed  as  metalloids^  with  the  formation  of  hydrates  which  differ 
very  materially  in  their  chemical  properties  from  the  hydrates  of  the 
metals.  It  combines  with  the  oxides  of  sulphur  and  phosphorus  to  form 
the  acids  of  those  elements: 

S03  +  H20  =  S04H2  P20&  +  3H20  ==  2PO4H,. 

Sulphur        Water.          Sulphuric  Phosphorus         Water.  Phosphoric 

trioxide.  acid.  pentoxide.  acid. 


42  GENERAL    MEDICAL    CHEMISTRY. 

Certain  of  these  acids  are  capable  of  combining  chemically  with  a  greater 
number  of  molecules  of  water  to  form  what  are  known  as  hydrates  of  the 
acids.  Thus,  there  are  definite  hydrates  of  sulphuric  acid  having  the  for- 
mulae— 

S04H2,  H26  and  SO,B2,  2H20, 

which  differ  materially  in  their  physical  properties  from  the  acid  SO4H2. 
That  these  hydrates  are  not  mere  mechanical  mixtures  is  shown  by  the 
fact  that  their  formation  is  attended  by  the  liberation  of  heat. 

Third. — Certain  substances  exhibit  a  great  tendency  to  absorb  water 
from  surrounding  bodies,  and  are  therefor  used  as  drying  agents;  cal- 
cium chloride,  sulphuric  acid  and  phosphorus  pentoxide  are  used  for 
drying  gases  in  the  laboratory.  The  preservative  action  of  alcohol  upon 
animal  substances  is  largely,  if  not  entirely,  due  to  its  power  of  absorbing 
water,  and  thus,  in  a  manner,  drying  the  putrescible  substances. 

Fourth. — The  chlorides  of  the  elements  of  the  third  and  fourth  classes 
are  either  insoluble  in  water,  or  soluble  without  decomposition;  the  corre- 
sponding compounds  of  the  second  class  are  decomposed  when  brought 
into  contact  with  water: 

PC13  +  3H20  =  P03H3  +  3HC1. 

Phosphorus        Water.        Phosphorous    Hydrochloric 
trichloride.  acid.  acid. 


Natural  Waters. 

From  whatever  source  natural  water  is  obtained,  it  always  holds  solid 
and  gaseous  matter  in  solution,  and  very  frequently  solid  matter  in  sus- 
pension as  well.  The  amount  and  nature  of  the  substances  held  in  solu- 
tion vary  greatly  with  the  purity  and  temperature  of  the  atmosphere 
through  which  the  water  has  fallen  as  rain,  with  the  nature  of  the  geo- 
logical strata  through  or  over  which  it  has  passed,  and  with  the  geo- 
graphical position  of  the  source  from  which  it  is  obtained. 

Natural  waters  may  be  divided  into  potable  and  impotable  waters. 
To  the  first  class  belong:  1st,  rain-water;  2d,  snow-  and  ice-water;  3d, 
spring- water  (fresh);  4th,  river-water;  5th,  lake-water;  6th,  well-water. 
To  the  second  belong:  1st,  stagnant  waters;  2d,  sea-water;  3d,  mineral- 
spring  waters. 

First. — Rain-icater  varies  much  in  purity  according  to  the  locali- 
ties in  which  it  is  collected  and  the  condition  of  the  atmosphere  at  the 
time.  It  holds  in  solution  comparatively  small  quantities  of  solid  matter, 
consisting  of  chlorides,  sulphates,  and  nitrates  of  sodium  and  ammonium. 
The  amount  of  hydrochloric  acid  is  greatest  in  the  neighborhood  of  salt 
water,  while  the  sulphate  and  nitrate  of  ammonium  are  most  abundant 
in  the  rain-water  collected  in  cities. 

The  following  table  of  analyses,  by  Dr.  R.  Angus  Smith,  indicates 
variations  in  the  quantity  of  solid  matter  in  rain-water  from  different 
localities: 


NATURAL    WATERS. 


RAIN-WATER. — AVERAGE  IMPURITIES  PER  MILLION  PARTS. 


- 

4 

•d  6 
If 

ft 

! 

1 

Where  collected. 

I 

i 

||| 

IS     .2 

4 

JU 

si 

P 

f 

"5 

02 

| 

|« 

1 

Is 

|2 

48.67 

2.73 

6 

none. 

.18 

.03 

.37 

Scotland,    five  sea-coast  country 

places  west  

12.28 

3.61 

29 

.14 

.48 

11 

.37 

Scotland,  eight  sea-coast  country 

places  east         

12.91 

7.66 

59 

2  44 

.99 

.11 

.47 

Scotland,   twelve  inland  country 

places       

3.38 

2.06 

61 

.31 

.53 

04 

.31 

England,    twelve  inland  country 

3.99 

5.52 

138 

none. 

1.07 

.11 

.75 

Scotland,  six  towns  (Glasgow  ex- 

5.86 

16.50 

282 

3.16 

3.82 

.21 

1.16 

Darmstadt            .              .      . 

97 

29  17 

2998 

1  74 

London  .                            

1  25 

20.49 

1645 

3  10 

3  45 

.21 

84 

England,  six  manufacturing  towns 

8.70 

34.27 

394 

8.40 

4.99 

.21 

.85 

5.83 

44.82 

768 

10.17 

5.96 

.25 

1.01 

8.97 

70.19 

782 

15.13 

9.10 

.30 

2.44 

In  commenting  upon  these  results,  Dr.  Smith  observes  that  the 
amount  of  chlorides  is  dependent  upon  the  distance  from  the  sea  and  the 
direction  of  the  prevailing  winds;  that  the  sulphuric  acid  increases  as  we 
go  inland,  and  is  derived  partially  from  the  combustion  of  coal,  and  par- 
tially from  the  decomposition  of  organic  matter;  and  that  when  the  pro- 
portion of  sulphuric  acid  to  hydrochloric  acid  is  greater  than  11.6  to  100. 
the  presence  of  the  excess  of  the  former  is  due  to  terrestrial  contamination. 

The  presence  of  nitrate  and  nitrite  of  ammonium  is  due,  to  a  certain 
extent,  to  the  decomposition  of  organic  matter,  but  principally  to  the 
combustion  of  coal,  as  is  shown  by  the  large  quantity  existing  in  the 
rain-water  collected  in  manufacturing  towns,  and  by  the  greater  propor- 
tion of  ammonia  found  in  rain-water  in  Lyons,  by  Bineau,  in  winter  than 
in  summer: 


Winter. 

16.3 


Spring. 


Summer. 

3.1. 


Autumn. 

4.0 


Average. 

6.8 


As,  during  its  formation  in  and  passage  through  the  atmosphere,  rain- 
water exposes  a  large  surface,  it  dissolves,  besides  solids  and  vapors, 
comparatively  large  quantities  of  gases — oxygen,  nitrogen,  carbon  diox- 
ide, and,  over  cities,  sometimes  hydrogen  sulphide  and  sulphur  dioxide 
— the  last-named  gases  being  produced  by  the  combustion  of  coal  con- 
taining sulphides.  According  to  Peligot,  a  litre  of  rain-water  at  Paris 
contains  2.4  c.c.  carbon  dioxide,  6.59  c.c.  oxygen,  and  14.0  nitrogen.  Ac- 
cording to  Gerardin,  rain-water  at  the  same  place  contains  from  5.18  c.c. 
to  8.  c.c.  of  oxygen  per  litre.  Great  care  should  be  taken,  in  the  collec- 
tion of  rain-water,  that  it  should  not  be  allowed  to  come  into  contact 
with  lead  surfaces,  as  the  comparatively  small  quantities  of  carbon  diox- 
ide and  carbonates,  and  the  comparatively  large  quantities  of  oxygen  and 
nitrates  which  it  contains,  render  it  peculiarly  prone  to  contamination 
with  that  metal  (see  p.  56). 


44  GENERAL    MEDICAL    CHEMISTRY. 

Rain-water  is  liable  to  contain  notable  quantities  of  organic  matter, 
especially  in  summer,  in  the  shape  of  vegetable  spores,  which  it  holds  in 
suspension;  the  presence  of  these  bodies  renders  the  water  liable  to  be- 
come stale  when  kept. 

Second- — Melted  snow  and  ice. — The  waters  obtained  from  these  two 
sources  differ  much  from  each  other  as  to  their  purity.  That  obtained 
from  ice  is  of  great  purity,  so  far  as  dissolved  matters  go;  for  these,  dur- 
ing crystallization,  are  to  a  great  extent,  although  not  completely,  separa- 
ted from  the  ice  and  retained  in  the  unfrozen  water.  Hassall  states  that 
in  freezing  a  small  portion  of  water  the  following  separation  took  place: 

Original  ,  Remaining 

water.  water. 

Total  solids 27.0  3.0  14.2 

Chlorine 1.94  0.9  

Lime 10.53  trace  14.11 

Water  obtained  by  melting  the  ice  of  sea-water  is  used  for  drinking- 
water  in  the  Arctic  regions.  Owing,  however,  to  the  separation  of  the 
dissolved  gases  together  with  the  solids,  ice-water  has  a  flat  taste. 

The  water  obtained  from  melted  snow  contains  about  the  same  pro- 
portion of  fixed  solid  matter  as  rain-water,  but  a  less  proportion  of  ammo- 
niacal  salts  arid  of  gases: 

Sodium  Ammonium  Ammonium 

chloride.  bicarbonate.  nitrate. 

Snow-water 0.01704  0.00129  0.00145 

Rain-water 0.00087  0.00189 

Sodium  Calcium  Organic 

sulphate.  sulphate.  matter. 

Snow-water 0.01563  0.00088  0.02385 

Rain-water 0.01007  0.00087  0.02486 

In  high,  mountainous  regions,  the  drinking-waters  used  are  largely 
mixtures  of  melted  ice  and  snow,  and  many  observers  have  attributed 
the  goitre  and  cretinism  prevailing  in  these  locations  to  the  use  of  such 
water  (see  p.  50). 

Third. — Spring-water  is  simply  rain-water  which  has  percolated 
through  the  subjacent  strata,  and,  owing  to  the  conformation  of  the 
ground  and  the  arrangement  of  the  strata,  has  made  its  appearance  upon 
the  surface  at  some  level  below  that  upon  which  it  originally  fell.  Dur- 
ing its  passage  through  the  earth,  in  which  it  is  frequently  subjected  to 
pressure,  it  dissolves  solid  and  gaseous  matter,  varying  in  kind  and  in 
quantity  with  the  nature  of  the  strata  with  which  the  water  has  been  in 
contact,  the  duration  of  such  contact,  and  the  pressure  to  which  it  is 
subjected. 

The  amount  of  extraneous  matter  dissolved  in  spring-water,  therefor, 
varies  greatly — from  the  water  of  some  saline  springs,  which  are  almost 
saturated  solutions  of  sodium  chloride,  to  the  pure  spring-water  which 
flows  from  the  side  of  a  porphyritic  or  quartz  mountain.  Between  these 
extremes  are  waters  of  all  degrees  of  purity. 

Spring-waters  from  igneous  rocks  and  from  the  older  sedimentary 
formations  are  sweet,  and  any  spring- water  may  be  so  considered  whose 
temperature  is  below  20°  and  which  does  not  contain  more  than  0.4 


NATURAL    WATERS. 


45 


gram  of  solid  matter  in  the  litre;  provided,  however,  that  a  large  propor- 
tion of  this  solid  residue  is  not  composed  of  salts  having  a  medicinal  action, 
and  provided  also  that  it  does  not  hold  sulphurous  gases  or  sulphides  in 
solution.  The  mineral  water  of  Plornbieres  contains  only  0.24  gram  of 
solid  matter  to  the  litre;  but  of  this,  0.0927  gram  is  sodium  sulphate; 
the  waters  of  Bagneres  contain  only  0.227  gram  solid  matters,  of  which 
0.064  gram  is  composed  of  sulphides;  it  also  has  hydrogen  sulphide  in 
solution. 

As  a  rule,  the  water  of  "  fresh  "  springs  is  cool  even  in  summer,  contains 
a  much  less  proportion  of  solid  matter  than  that  mentioned  above,  and 
has  a  crisp  and  agreeable  flavor,  owing  to  the  almost  entire  absence  of 
organic  matter  and  the  presence  of  a  comparatively  large  amount  of 
dissolved  oxygen.  Spring-waters  from  limestone  and  dolomite  formations 
contain  excessive  quantities  of  the  salts  of  magnesium  and  calcium,  in 
consequence  of  which,  without  being  valuable  as  "mineral  waters,"  their 
usefulness  as  drinking-water  is  greatly  diminished  or  destroyed  (see  p.  49). 

Artesian  wells  may  be  regarded  as  artificial  springs,  formed  by  boring 
perpendicularly  into  the  earth,  in  a  low-lying  district  surrounded  by  more 
elevated  ground,  until  a  permeable  layer  included  between  two  strata  of 
impermeable  rock  is  reached,  the  strata  being  so  curved  that  their  outcrop 
is  in  the  surrounding  elevated  district.  When  such  a  well  has  been  suc- 
cessfully bored,  usually  at  great  cost,  it  furnishes,  without  pumping,  an 
abundant  supply  of  water,  more  or  less  pure,  according  to  the  nature  of 
the  strata  through  which  the  water  has  percolated.  The  following  table 
indicates  the  nature  of  the  impurities  present  in  the  waters  from  springs 
and  artesian  wells: 


Origin. 

Fixed 
residue. 

Ca. 

Mg. 

Cl. 

Organic 
matter. 

Authority. 

Spring       near      Besancon, 
France 

0.3085 

0.1046 

0.0008 

0.0016 

H.  Deville. 

Spring  in  Surrey,  England. 
Sprin0*  near  Auburn  Me 

0.225 
0.0349 

0.0626 

0.0025 

0.0121 

0.0136 
0.0022 

Graham,  Miller 
&  Hofmann. 
S.  D.  Hayes. 

Artesian    well    at  Grenelle, 
France      .      .               .... 

0.143 

0.0272 

0.004 

0.0052 

0.002 

Payen. 

Artesian  well  at    Trafalgar 
Square,  London  

0.9915 

0.0188 

0.0091 

0.1742 

0.013 

Abel  &  Rowney, 

Artesian    well    at   Dedham, 
Mass.            .            .        ... 

0  0888 

0.019 

S.  D.  Hayes. 

Artesian  well  at  Boston  .... 
Brewery  Spring,  Boston..  .  . 

0.945 
0.2629 



'  ' 

0.0317 
0.0288 

i  t 
(t 

Some  of  these  artesian  wells  are  of  great  celebrity:  that  at  Grenelle, 
in  the  outskirts  of  Paris,  has  a  depth  of  1,748  feet,  and  furnishes  516  gal- 
lons per  minute,  the  water  rising  to  a  height  of  32  feet  from  the  level  of 
the  ground. 

Fourth. — River-water  is  composed  of  spring- water,  rain-water,  and 
the  drainage- water  from  the  country  through  which  the  river  flows;  it  con- 
tains also  ice-  and  snow-water  at  all  seasons,  if  the  origin  of  the  river  be 
from  a  glacier  or  from  above  the  snow-line;  and  in  the  lowlands  in  winter 
and  early  spring;  or  sea- water,  if  it  be  sufficiently  near  the  ocean  to  be 
under  tidal  influence.  River-water  may,  therefor,  be  excellent  or  en- 
tirely unfit  for  drinking.  A  river  flowing  rapidly  through  a  granitic  region 


46 


GENERAL    MEDICAL    CHEMISTRY. 


distant  from  the  sea,  furnishes,  unless  polluted  by  man,  a  pure,  bright,  and 
highly  aerated  water;  while  another,  flowing  sluggishly  through  rich,  allu- 
vial lands,  yields  a  muddy,  unaerated  water,  holding  large  quantities  of 
mineral  and  organic  matter  in  solution  and  in  suspension. 

The  amount  of  mineral  matter  held  in  solution  in  river-water  increases 
with  the  distance  it  has  travelled.  The  water  of  a  mountain  torrent  in 
the  valley  of  the  Isere,  near  its  origin  in  a  glacier,  was  found  by  Grange 
to  contain  0.0201  gram  of  mineral  matter  per  litre  ;  the  water  from  the 
same  stream,  2,000  metres  (1J  mile)  below,  contained  0.0753  gram  per 
litre.  The  waters  of  the  Rhine  at  Bale  contain  0.1694  gram  of  fixed  resi- 
due per  litre  (Pagenstecher);  at  Strasbourg,  about  80  miles  below,  0.2317 
gram  (H.  Deville);  and  at  Emmerich,  about  400  miles  below,  0.289 
gram  (Milller).  The  purity  of  river -water  depends  largely  upon  the 
density  of  the  population,  and  upon  the  nature  of  the  industries  followed 
upon  its  banks  ;  indeed,  the  two  principal  sources  of  the  pollution  of  river- 
waters  are  the  discharge  into  them  of  the  sewage  of  cities  and  the  waste 
products  of  factories.  In  its  passage  through  a  large  city,  river- water  re- 
ceives organic  matter,  ammonia,  chlorides,  sulphates,  phosphates,  and 
carbon  dioxide,  while  it  loses  oxygen.  The  amount  of  free  nitrogen  re- 
mains nearly  the  same.  In  the  following  table,  compiled  from  the  analyses 
of  R.  A.  Smith,  Graham,  Miller  and  Hofmann,  and  Ashley,  are  indicated 
the  changes  which  take  place  in  the  amounts  of  extraneous  substances 
dissolved  in  the  water  of  the  Thames,  produced  during  its  passage 
through  London — these  changes  occurring  notwithstanding  the  fact  that 
the  sewage  is  discharged  outside  of  the  city,  at  a  point  below  Woolwich, 
distant  about  twelve  miles  from  London  Bridge,  and  that  the  contamina- 
tion is  caused  by  the  addition  of  a  quantity  of  filth  exceedingly  small  as 
compared  with  the  total  sewage  of  the  city. 


Water  taken  at 

0. 

N. 

coa 

Solids. 

CL 

Organic 
matter. 

Hammersmith  .... 
Chelsea  

4.1 

15.1 

0*.46 

oisoi 

0.0175 

0.034 

Waterloo  Bridge.  . 
London  Bridge  .  .  . 

1.5 
0  25 

16.2 
14  5 

27.2 

v 

0.4084 

o'.0636 

(f.'lOO 

The  amounts  of  dissolved  gases  are  given  in  c.c.,  and  those  of  the 
solids  and  chlorine  in  grams  per  litre. 

The  question  of  the  most  advantageous  disposal  of  the  sewage  of  towns 
and  cities  is  one  which,  although  it  has  been  the  subject  of  a  vast  amount 
of  discussion  and  investigation,  is  still  subjudice.  If,  as  is  unfortunately 
often  the  case,  the  sewage  is  discharged  into  the  nearest  stream,  the  water 
is  contaminated  to  such  an  extent  that  it  is  not  only  useless  for  drinking, 
but  also  a  stench  in  the  nostrils  of  the  inhabitants  below.  There  is  also 
an  economic  objection  to  this  plan,  in  that  a  large  quantity  of  valuable  fer- 
tilizer is  thus  wasted.  Methods  have  repeatedly  been  suggested  and  sub- 
jected to  the  test  of  experiment,  for  utilizing  human  excreta  as  fertilizers. 
These  are  of  four  kinds,  and,  unfortunately,  are  all  open  to  objections  more 
or  less  serious. 

In  Holland  and  Belgium  a  very  primitive  method  is  followed:  the  de- 


NATURAL    WATERS.  47 

jections  are  collected  in  cisterns  or  barrels,  whence  they  are  removed  to 
larger  depots,  at  which  the  farmers  purchase  their  supplies  as  needed — us- 
ing the  material  without  any  preparation  beyond  fermentation  and  dilu- 
tion with  water.  In  Paris  the  excreta  are  not  allowed  to  enter  the  sewers, 
but  are  collected  in  cisterns,  whence  they  are  pumped  at  night  and  carried 
to  a  suburb,  which  will  be  easily  recognized  by  the  traveller,  be  he  never  so 
severely  afflicted  with  catarrh.  Here  the  liquid  portions  are  separated 
and  sold  for  manure  under  the  name  of  "  eaux  vannes,"  and  the  solid  por- 
tions are  subjected  to  a  slow  drying  process,  to  yield  a  brown,  odorless  fer- 
tilizer called  "  poudrette."  These  two  methods  of  dealing  with  human 
excreta  from  cities  are  open  to  the  serious  objection  that  the  material  is 
allowed  to  collect  and  exhale  its  noxious  and  disgusting  effluvia  in  the 
midst  of  the  population,  an  objection  most  serious  among  the  poorer  house- 
holders, who,  to  avoid  the  expense  of  frequent  cleansing  of  the  cisterns, 
fail  to  use  the  necessary  quantity  of  water  for  flushing  the  closets. 

Of  late  years  frequent  attempts  have  been  made  to  use  the  mixture  of 
surface-water  and  excreta  collected  from  the  sewers  by  discharging  it  di- 
rectly upon  the  laud.  Experiments  upon  a  large  scale  have  been  made  in 
the  neighborhood  of  Milan,  of  Edinburgh,  of  Banbury,  at  Norwood,  and 
at  the  Lodge  Farm,  near  London.  This  plan,  which  was  not  attended  with 
the  financial  success  expected  by  its  promoters,  is  also  open  to  serious  ob- 
jections from  a  sanitary  point  of  view.  It  is  certainly  as  favorable  to  the 
propagation  of  disease,  especially  cholera,  typhoid,  and  entozoic  diseases, 
as  is  the  method  of  discharging  the  sewage  into  the  rivers. 

A  plan  which  is  destined  to  yield  the  best  results,  when  all  idea  of  at- 
tempting to  follow  it  with  pecuniary  profit  as  the  principal  object  shall 
have  been  abandoned,  is  that  of  collecting  the  sewage  at  some  point  in 
the  neighborhood  of  the  city,  and  there  subjecting  it  to  disinfection  with 
a  view  to  rendering  its  subsequent  use  as  a  fertilizer  safe  and  inoffensive. 

It  is  an  undeniable  fact  that  organic  matter  in  solution  or  in  suspen- 
sion in  rapidly  moving  water  is  decomposed  and  oxidized  more  or  less 
quickly;  urea  is  soon  decomposed  into  carbonic  anhydride  and  ammonia;  al- 
buminoid substances  are  much  more  slowly  oxidized,  their  nitrogen  being 
converted  into  nitrates,  nitrites,  and  ammoniacal  compounds.  Although 
this  decomposition  takes  place  in  the  course  of  a  few  miles  in  a  stream 
whose  current  is  rapid,  provided  the  admixture  of  sewage-matter  be  not 
in  too  great  proportion,  it  is  impossible  to  state  at  what  a  distance  from 
the  source  of  contamination  the  water  of  a  river  receiving  sewage  dur- 
ing an  epidemic  of  typhoid  or  of  cholera,  would  become  incapable  of  com- 
municating the  disease,  if,  indeed,  there  be  any  limit. 

Quite  as  serious  a  source  of  contamination  of  river-water  exists  in  the 
discharge  into  it  of  the  waste  products  from  factories,  etc.  These  con- 
taminations are  as  various  in  their  nature  as  the  processes  which  give  rise 
to  them;  the  question  of  their  disposal  is,  although  much  more  simple 
than  that  in  which  sewage  is  concerned,  not  likely  to  be  quickly  solved, 
owing  to  the  magnitude  of  the  financial  interests  involved.  Manufac- 
turers should  be  obliged  to  discharge  their  waste  products,  when  these 
are  of  such  a  nature  as  neither  to  contaminate  the  air,  nor  yet  to  impede 
navigation,  only  into  rivers  whose  waters  are  naturally  unfit  for  drink- 
ing. When  from  any  cause  this  course  cannot  be  followed,  they  should 
adopt  some  process  (which  will  certainly  be  devised  pro  re  natd)  of  dis- 
posing of  their  refuse  in  such  a  way  as  to  avoid  pollution  of  the  water. 

The  nature  and  amount  of  the  substances  held  in  solution  in  river- 


48  GENERAL   MEDICAL   CHEMISTRY. 

water  varies  materially  with  the  season.  The  warmer  the  water  the  more 
solid  and  the  less  gaseous  matter  it  contains.  In  warm  weather  the  ten- 
dency of  organic  matter  to  putrefaction  is  greater,  as  is  also  the  rapidity 
of  its  destruction  by  oxidation.  During  those  periods  when  water- 
courses are  swollen  by  rains  and  by  the  melting  of  snow,  the  amount  of 
dissolved  solid  matter  is  relatively  diminished,  while  the  amount  of  sus- 
pended solids  is  increased.  River-water,  at  the  first  part  of  the  flood 
period,  contains  an  amount  of  chlorine  much  greater  in  proportion  to 
total  solids  and  to  hardness  than  at  other  periods.  The  water  which 
comes  down  during  the  first  part  of  the  flood  has  not  penetrated  deeply 
into  the  earth,  and  has  therefor  had  but  little  opportunity  of  becoming 
charged  with  earthy  salts;  it  has,  however,  dissolved  the  more  soluble 
chlorides  from  the  surface.  At  later  periods  the  water,  penetrating  more 
deeply  below  the  surface,  becomes  more  highly  charged  with  calcareous 
salts. 

Fifth — Lake-water. — Fresh  lakes,  being,  as  a  rule,  simply  expansions 
of  rivers,  or  points  where  many  of  their  tributaries  unite,  their  water  is 
very  similar  to  that  of  the  rivers  flowing  into  or  outtof  them,  with  the 
exception  that,  as  the  lakes  expose  a  large  surface  to  the  air,  and  as  the 
water  is  kept  in  motion  both  by  the  current  and  by  the  action  of  the 
winds,  the  removal  of  organic  matter  by  oxidation  is  more  active  than  in 
rivers  not  having  a  very  rapid  current.  Lakes  form  natural  reservoirs 
from  which  the  water-supply  of  many  cities  is  obtained.  Those  cities 
situated  upon  the  borders  of  large  lakes  are  assured  of  an  abundant  sup- 
ply of  pure  water,  it  being  only  required  to  raise  it  to  a  sufficient  height 
for  distribution.  Municipalities  less  fortunately  situated  resort  to  the 
construction  of  more  or  less  elaborate  works,  for  the  collection  and  stor- 
age of  water  from  a  system  of  lakes  and  rivers. 

Sixth —  Well-water  may  be  very  good  or  very  bad.  In  some  in- 
stances the  well  is  simply  a  collecting  reservoir  dug  over  a  natural  spring. 
When  this  is  the  case,  if  it  be  in  such  a  situation  as  to  be  free  from 
contamination,  the  water  is  essentially  spring- water  (q.  v.).  In  most 
cases,  however,  a  well  is  simply  a  hole,  deep  or  shallow,  with  walls  well 
or  badly  constructed,  into  which  the  surface-water  percolates  from  the 
thin  stratum  through  which  the  well  is  dug.  Such  water  is  almost  always 
highly  charged  with  organic  matter,  insipid  or  sweetish  in  taste,  and 
should  be  carefully  avoided. 

But  the  character  of  well-water,  whatever  its  source,  depends  largely 
upon  its  position.  As  a  rule,  wells  are  constructed  near  to  human  habita- 
tions, and  are  thus  very  liable  to  contamination  with  organic  matter,  either 
from  the  surface,  or,  more  frequently,  by  the  breaking  of  a  house-drain 
and  the  filtration  of  its  contents,  through  a  few  feet  of  intervening  soil,, 
into  the  water  of  the  well  (see  p.  52). 

Of  late  years  "  driven  wells "  have  been  largely  resorted  to  in  this 
country.  They  are  formed  by  driving  a  pointed  iron  tube  into  the  earth, 
increasing  the  length  of  tube  by  sections  and  removing  any  earth  which 
may  have  found  its  way  within  the  tube,  until  a  supply  of  water  is  ob- 
tained, either  by  its  spontaneous  rise  in  the  tube,  or,  more  commonly,  by 
pumping.  The  water  so  obtained  is  similar  in  character  to  that  from 
surface-wells,  and,  while  it  may  be  good  where  the  location  is  in  an  open 
and  unmanured  location,  it  is  to  be  looked  upon  with  grave  suspicion  if 
the  well  be  driven  in  any  situation  where  the  surface-water  is  liable 
to  become  contaminated  with  the  excreta  of  men  or  animals. 


IMPURITIES    IN    POTABLE    WATEK.  49 

Impurities  in  Potable  Water. 


Characters  of  a  good  water. — It  should  be  cool,  limpid,  and  odorless. 
It  should  have  an  agreeable  taste,  neither  flat,  salty,  nor  sweetish,  and  it 
should  dissolve  soap  readily,  without  the  formation  of  insoluble,  flocculent 
material.  Any  water  which  does  not  possess  these  qualities  is  not  fit  for 
drinking  ;  but  it  is  by  no  means  true  that  any  water  which  does  possess 
them  is  not  to  be  looked  upon  with  suspicion.  To  determine  whether  or 
no  any  given  water  is  potable,  a  more  careful  examination  into  the  nature 
and  quantity  of  .foreign  substances  present  is  necessary.  These  sub- 
stances may  be  either  in  solution  or  in  suspension. 

First — Total  solids. — We  have  seen  that  all  natural  waters  are  more 
or  less  charged  with  solid  mineral  matter,  a  certain  proportion  of  which 
seems  to  be  necessary  to  health.  On  the  other  hand,  if  the  amount  of 
solid  matter  dissolved  be  excessive,  the  water  is  both  unpalatable  and 
unhealthy.  In  the  following  table  is  given  the  number  of  grams  per  litre 
of  total  solids  in  various  waters  : 

Distilled  water ..  0.0017  I  Croton..  0.0918 


London— Thames  Co 0.2646 

London— New  River  Co  . .    0.2509 

London — Kent  Co 0.3780 

Rhine,  at  Basle 0.1694 


Boston — Cochituate 0 .0548 

Charlestown— Mystic 0.0972 

Copenhagen 1 . 700 

Atlantic — surface..  .   34.700 


Seine,  at  Bercy 0 .2544  i  Dead  Sea— surface 27 .078 


Spree,  at  Berlin 0 . 114 

Glasgow — Loch  Katrine  . .   0.0328 


Dead  Sea— 300  metres. .  .278.135 


The  amount  of  total  solids  in  potable  waters  varies  from  0.05  to  0.4 
gram  per  litre,  the  amount  being,  as  a  rule,  less  in  the  waters  supplied 
to  American  cities  than  in  those  consumed  by  the  urban  populations  of 
Europe.  The  solids  dissolved  in  water,  their  nature  not  being  taken  into 
consideration,  do  not  impair  its  usefulness  as  a  drink,  unless  they  be 
present  in  a  quantity  greater  than  0.4  to  0.5  gram  per  litre. 

The  determination  of  the  amount  of  total  solids  is  easily  conducted  : 
25  c.c.  of  the  filtered  *  water  are  evaporated  to  dryness  in  a  previously 
weighed  platinum  dish  over  a  water-bath.  After  cooling  in  a  drying-box, 
the  dish,  with  the  contained  residue,  is  weighed  ;  the  increase  in  weight, 
multiplied  by  40,  gives  the  amount  of  total  solids  per  litre. 

Second — Hardness. — Of  the  solid  matters  dissolved  in  potable  waters, 
the  greater  part  is  usually  made  up  of  salts  of  calcium,  accompanied,  as  a 
rule,  by  small  quantities  of  salts  of  magnesium.  The  calcium  salt  present 
is  usually  the  carbonate  or  the  sulphate;  sometimes  the  chloride,  phos- 
phate, or  nitrate.  Calcium  carbonate  is  almost  insoluble  in  pure  water; 
but  in  water  charged  with  carbon  dioxide  a  more  soluble  bicarbonate 
is  formed,  which  remains  in  solution  until  the  carbon  dioxide  is  ex- 
pelled by  heat,  whenever  the  carbonate  is  present  in  quantity  greater 
than  0.5  gram  per  litre.  The  sulphate  is  present,  being  sparingly  soluble, 
in  many  excellent  waters.  In  quantity  it  should  not  exceed  0.02  gram 
per  litre.  The  presence  of  the  phosphate  is  probably  more  general  than 
published  analyses  would  lead  one  to  suppose,  as  it  is  widely  disseminated 

*  Suspended  solids  must  be  determined  by  the  method  given  on  p.  57. 
4 


50  GENERAL    MEDICAL    CHEMISTRY. 

in  the  mineral  world,  and  the  processes  used  for  determining  phosphoric 
acid  lack  accuracy  when  applied  to  such  small  quantities  as  we  have  here 
to  deal  with.  The  chloride  is  rarely  present,  and  only  in  small  quantity. 
The  nitrate  is  only  found  in  waters  contaminated  with  organic  matter,  at 
the  expense  of  whose  nitrogen  the  nitric-acid  is  formed  by  oxidation. 

A  water  which  contains  an  excess  of  calcium  salts  is  said  to  be  hard, 
while  one  not  so  charged  is  said  to  be  soft.  If  the  hardness  be  due  to  the 
presence  of  the  carbonate,  it  is  temporary,  as,  upon  the  application  of 
heat,  carbon  dioxide  is  driven  off,  and  the  excess  of  carbonate,  being  no 
longer  soluble,  is  precipitated.  A  permanently  hard  water  owes  its  hard- 
ness to  the  presence  of  the  sulphate,  which  remains  in  solution  after  heat- 
ing, being  dissolved  simply  by  virtue  of  its  own  solubility. 

It  is  a  matter  of  common  experience  that  a  hard  water  is  not  as  ser- 
viceable for  domestic  purposes  as  soft  water.  If  we  attempt  to  dissolve 
soap  in  a  water  charged  with  calcic  and  magnesic  salts,  the  first  portions 
are  decomposed  with  the  formation  of  the  insoluble  calcium  and  magne- 
sium palmitate  and  oleate,  which  separate  as  flocculent  precipitates,  and 
not  until  the  earthy  salts  have  thus  been  removed  will  the  water  be  capa- 
ble of  dissolving  or  forming  a  lather  with  soap.  Vegetables,  when  boiled 
in  hard  water,  do  not  soften  as  readily  as  when  the  water  is  soft;  moreover, 
a  hard  water  is  difficult  of  digestion,  and  is  liable  to  produce  disorders  of 
digestion,  especially  in  those  unaccustomed  to  its  use. 

Magnesium  salts,  sulphate  and  carbonate,  frequently  accompany  the  cor- 
responding calcium  compounds,  although  in  much  smaller  quantity.  Their 
influence  upon  the  quality  of  the  water  is  the  same  as  that  of  the  calcium 
salts,  with  the  difference  that  if  the  quantity  of  magnesic  salt  exceeds  0.02 
gram  per  litre,  the  water  is  to  some  extent  purgative.  The  opinion  advanced 
by  Grange  and  sustained  by  others,  that  the  occurrence  of  goitre  and 
cretinism  is  due  to  an  excess  of  magnesium  salts  in  the  water,  is  not  well 
founded.  Analysis  has  shown  the  presence  of  greater  quantities  of  mag- 
nesium salts  in  the  water  of  districts  where  these  diseases  are  unknown 
than  exists  in  the  waters  used  in  localities  where  they  are  very  prevalent. 

Although  an  excess  of  calcareous  salts  in  water  renders  it  unfit  for  do- 
mestic use,  within  proper  limits,  0.3  gram  per  litre,  the  carbonate  and 
phosphate  of  calcium  are  not  only  not  deleterious,  but  beneficial  constit- 
uents, as  they  supply  a  proportion  of  those  salts  required  by  the  economy, 
especially  in  the  first  years  of  life. 

It  is  rarely  'necessary  to  determine  the  amount  of  calcium  and  magne- 
sium salts  present  in  water  with  accuracy.  It  is,  however,  frequently  of 
importance  to  determine  the  degree  of  hardness,  which  may  be  measured 
with  tolerable  exactness  by  means  of  a  process  suggested  by  Dr.  Clark  in 
1847,  and  based  upon  the  soap-destroying  power  of  the  earthy  salts.  The 
method,  as  given  by  Wanklyn  and  as  usually  applied,  is  very  simple. 
Seventy  cubic  centimetres  of  the  water  to  be  tested  are  placed  in  a  glass- 
stoppered  bottle  having  a  capacity  of  250  c.c.  From  a  burette  an  alco- 
holic solution  of  soap  is  added,  and  after  each  addition  the  bottle  is  shaken 
and  laid  upon  its  side  for  five  minutes.  If  at  the  end  of  that  time  the 
lather  remains,  enough  soap-solution  has  been  added;  if  not,  the  addition 
must  be  continued  until  the  lather  persists  for  five  minutes.  If  more  than 
16  c.c.  of  soap-solution  are  used,  70  c.c.  of  distilled  water  must  be  added, 
as  a  lather  is  not  readily  formed  if  the  proportion  of  alcohol  become  too 
great.  Having  added  sufficient  soap-solution,  the  degree  of  hardness  is 
indicated  by  the  number  of  cubic  centimetres  of  soap-solution  used  minus  1. 
Thus,  if  15  c.c.  soap-solution  have  been  used,  the  degree  of  hardness  is  14. 


IMPURITIES    IN    POTABLE    WATER.  51 

If  from  the  degree  of  hardness  we  subtract  1,  we  have  approximately  the 
number  of  grains  of  calcium  carbonate,  or  of  salts  having  an  equal  soap- 
destroying  power,  in  a  gallon  of  the  water. 

To  prepare  the  soap-solution,  air-dried  white  castile  soap  is  reduced  to 
thin  shavings,  of  which  10  grams  are  dissolved  in  a  litre  of  weak  alcohol, 
having  a  specific  gravity  of  about  0.949.  The  solution  must  not  be  fil- 
tered; usually  it  is  clear,  but,  if  turbid,  it  should  be  shaken  before  using. 

Having  made  the  soap-solution,  it  is  necessary  to  determine  its  actual 
strength,  as  soap  is  a  substance  which  cannot  be  accurately  weighed.  To 
this  end  a  solution  of  calcium  chloride  of  known  strength  is  made  by  dis- 
solving 1.11  gram  of  pure,  recently  fused  calcic  chloride  in  a  litre  of  water; 
10  c.c.  of  this  solution,  mixed  with  60  c.c.  of  distilled  water,  should  require, 
for  the  formation  of  a  persistent  lather,  11  c.c.  of  soap-solution.  If  more 
or  less  of  the  soap-solution  be  required,  it  must  be  concentrated  or  diluted 
in  the  proportion  of  the  deficiency  or  excess  to  bring  it  to  the  proper 
strength. 

By  this  method  the  total  hardness  is  determined.  If  it  be  desirable 
to  know  what  portion  of  this  is  temporary  or  permanent,  the  total  hard- 
ness is  first  determined.  Another  sample  of  the  water  is  then  boiled,  and 
from  this  70  c.c.  are  taken  after  filtration,  in  which  the  permanent  hard- 
ness is  determined  as  above  ;  the  difference  is  temporary  hardness. 

It  sometimes  occurs  that  a  water,  comparatively  pure  as  to  organic 
matters,  exhibits  a  tendency  to  produce  diarrhoaa  ;  in  this  case  it  is  well 
to  determine  the  amount  of  magnesian  salts  present.  A  litre  of  water  is 
evaporated  to  dryness  in  a  platinum  dish;  the  residue  is  moistened  with 
hydrochloric  acid,  a  small  quantity  of  water  is  added,  and  the  solution  fil- 
tered. To  the  united  filtrate  and  washings  ammonium  hydrate  and  solu- 
tion of  ammonium  oxalate  are  added  in  excess;  the  liquid  is  then  heated 
and  filtered.  To  the  filtrate  more  ammonia  is  added,  and  the  mixture  al- 
lowed to  stand.  If  after  twelve  hours  a  precipitate  have  formed,  the  fluid 
is  again  filtered.  To  the  clear  liquid,  which  should  not  be  more  than  40  c.c. 
in  bulk,  solution  of  phosphate  of  sodium  and  ammonium  hydrate  are 
added  in  excess,  and  the  mixture  set  aside  for  twenty-four  hours.  The 
precipitate  is  now  collected  on  a  filter,  washed  with  ammoniacal  water, 
dried,  ignited,  and  weighed.  The  weight  of  the  residue,  multiplied  by 
0.36036,  equals  the  weight  of  magnesia  in  a  litre  of  the  water. 

A  good  drinking-water  should  not  have  a  hardness  of  more  than  15, 
and  should  not  contain  more  than  0.015  gram  per  litre  of  magnesium. 

Third —  Chlorides. — The  chlorides  of  the  alkaline  and  earthy  metals  oc- 
-cur  in  varying  quantity  in  all  natural  water.  The  occurrence  of  these  salts 
in  quantities  not  sufficient  to  render  their  presence  readily  detectable  by 
the  taste  is  of  no  importance  per  se /  but,  in  connection  with  the  presence 
of  organic  matter,  a  determination  of  the  amount  of  chlorine  affords  a 
valuable  index  to  the  probable  source  of  the  organic  matter.  The  most 
dangerous  of  organic  contaminations  is  that  by  admixture  of  animal  ex- 
creta ;  the  presence  of  vegetable  organic  matter  is,  comparatively  speak- 
ing, innocuous.  Vegetable  contamination  brings  with  it  a  very  small 
amount  of  chlorine,  while  urine,  which,  when  the  water  is  polluted  with 
sewage,  forms  the  bulk  of  the  contaminating  admixture,  contains  large 
quantities  of  chlorides.  If,  therefor,  a  well-water  be  found  to  contain  an 
excess  of  chlorides,  it  is  to  be  looked  upon  with  suspicion;  and  if  at  the 
same  time  there  be  an  excess  of  nitrogenized  material,  there  remains  but 
small  doubt  that  the  well  contains  diluted  urine.  So  true  is  this  that  at 
times,  when  results  must  be  obtained  rapidly,  as  during  an  epidemic,  the 


52  GENERAL    MEDICAL    CHEMISTRY. 

best  course  for  the  analyst  to  pursue  is  to  determine  the  amount  of 
chlorine  in  each  source  of  supply,  and  to  condemn  those  containing  more 
than  .015  grain  per  litre  (one  grain  per  gallon)  of  chlorine.  Whenever 
it  is  possible,  however,  a  determination  of  organic  matter  should  be  made, 
and  the  result  considered  in  connection  with  the  quantity  of  chlorine 
before  deciding  for  or  against  a  water. 

The  determination  of  the  amount  of  chlorine  is  easily  effected  by 
means  of  a  solution  of  silver  nitrate  containing  4.79  grams  per  litre: 
100  c.c.  of  the  water  to  be  tested  are  placed  in  a  beaker  ;  a  few  drops  of 
a  solution  of  potassium  chromate,  enough  to  communicate  a  distinctly 
yellow  tinge,  are  added ;  the  reaction  is  determined,  and,  if  necessary, 
the  mixture  is  rendered  faintly  alkaline  by  the  addition  of  a  solution  of 
sodium  carbonate.  The  silver  solution  is  now  allowed  to  flow  in,  drop 
by  drop,  from  a  burette,  the  fluid  in  the  beaker  being  constantly  stirred, 
until  the  white  precipitate  assumes  a  faint  reddish  tinge.  At  this  time 
the  reading  of  the  burette  is  taken;  each  cubic  centimetre  of  silver  solu- 
tion added  represents  0.001  gram  chlorine  in  100  c.c.  of  water,  or  0.01 
per  litre. 

Fourth  —  Organic  matter. — Although  the  presence  in  a  water  of  or- 
ganic substances,  i.  a.,  substances  into  whose  composition  carbon  enters 
as  an  element,  cannot  be  considered  as  condemnatory,  there  is  no  reason 
for  doubting  that  the  most  serious  of  contaminations  of  potable  waters 
are  those  caused  by  the  presence  of  organic  matters  containing  nitrogen, 
both  from  the  putrescible  nature  of  these  substances,  and  from  the  in- 
dication afforded  by  their  presence  of  the  existence  in  the  water  of 
animal  excreta,  as  well  as  the  presence  under  suitable  conditions  of  the 
causes  of  the  disease,  be  they  germs  or  poisons.  Every  potable  water 
contains  small  quantities  of  organic  matter  of  vegetable  origin,  which  are- 
of  110  significance,  provided  the  quantity  be  small  and  the  water  be  taken 
from  a  river,  lake,  or  other  body  of  moving  water.  If,  however,  a  well- 
water,  or  other  still  water,  contain  much  vegetable  organic  matter  (its 
vegetable  nature  being  indicated  by  the  absence  or  deficiency  of  chlorides), 
the  source  is  to  be  condemned  for  that  reason  alone. 

A  much  more  serious  organic  contamination  is  with  nitrogenous 
matter  of  animal  origin.  Although  our  knowledge  of  the  nature  of  the 
products  of  decomposition  of  these  substances  is  still  quite  crude,  it  is 
certain  that  among  them  are  substances  having  a  pronounced  tendency 
to  produce  low  forms  of  fever,  and  to  render  those  subjected  to  their  in- 
fluence ready  victims  to  epidemic  disorders.  Whatever  ill  effects  may 
result  from  the  use  of  waters  polluted  by  the  excreta  of  healthy  individ- 
uals, the  evil  becomes  much  more  serious  during  the  prevalence  of  certain 
diseases.  There  can  remain  no  doubt  that  cholera  and  typhoid  are  trans- 
mitted largely,  if  not  exclusively,  by  the  use  of  water  into  which  the 
excreta  of  a  sufferer  from  the  disease  have  found  their  way. 

The  investigations  of  Mr.  J.  N.  Radcliffe,  on  the  cholera  in  London 
in  1866,  have  shown  that  the  disease  was  sharply  limited  to  those  por- 
tions of  the  metropolis  supplied  with  water  from  the  Old  Ford  reservoirs 
of  the  East  London  Water  Company,  the  earliest  unquestionable  out- 
breaks of  the  disease  having  appeared  within  half  a  mile  of  these  reser- 
voirs.* In  a  subsequent  report  Dr.  Buchanan  traced  the  source  of  the 
epidemic  of  typhoid,  which  occurred  at  Guildford,  directly  to  contamina- 
tion of  water-supply.  The  town  is  supplied  with  a  double  system  of  high 

*  Report  of  the  Medical  Officer  of  the  Privy  Council,  I860  (9th),  p.  205-331. 


IMPURITIES    latf    POTABLE    WATER.  53 

and  low  distribution,  and  with  very  few  exceptions  the  disease  was 
limited  to  those  using  the  high  service.*  In  the  same  year  epidemics  of 
typhoid  occurred  also  at  Winterton  and  at  Terling;  in  both  instances 
they  were  distinctly  referable  to  contamination  of  the  water  with  sewage.f 
Similar  conclusions  have  been  arrived  at  in  investigations  of  the  causes  of 
many  other  epidemics. 

Several  processes  have  been  devised  for  the  determination  of  the 
amount  of  organic  matter  present  in  drinking-water;  of  these  some  are 
very  readily  applied,  and  are  inaccurate  in  proportion  to  their  facility. 
Probably  the  method  best  adapted  to  use  by  the  practitioner  in  an  im- 
ergency  is  that  which  has  the  least  claim  to  exactness  of  results.  This 
consists  in  simply  partially  filling  a  clean  bottle  with  the  water  to  be 
tested,  and,  after  strong  agitation,  inhaling  the  air  of  the  bottle  through 
the  nostrils.  The  presence  or  absence  of  an  injurious  amount  of  organic 
matter  is  inferred  from  the  presence  or  absence  of  a  disagreeable  odor, 
however  faint,  of  the  inhaled  air.  The  only  advantage  of  this  method  is 
the  facility  of  its  application;  it  is  exceedingly  rough,  and  should  be  used 
only  when  time  presses. 

Another  method  is  the  permanganate  test,  which  must  be  mentioned 
here  that  it  may  be  avoided,  especially  as  it  has  received  a  quasi- 
official  indorsement  at  the  hands  of  the  New  York  Board  of  Health.  In 
the  report  of  that  body  for  1873, J  directions  are  given  for  testing  water 
by  dropping  into  it  a  solution  of  potassium  permanganate  and  by  the 
discharge  of  color  determining  not  only  the  presence,  but  also  the 
amount  of  organic  matter  in  the  water.  Drs.  Frankland,  Wanklyn,  and 
Fox  have  clearly  shown  that  the  process  is  vitiated  by  both  plus  and 
minus  errors.  Any  substance  capable  of  abstracting  oxygen  from  the 
permanganate  will  effect  its  decolorization,  whether  the  substance  be  or- 
ganic or  not.  On  the  other  hand,  in  the  conditions  under  which  the  test 
is  applied,  organic  substances  of  an  albuminoid  nature  and  urea  are  not 
readily  oxidized  by  permanganate.  By  the  use  of  this  test,  therefor,  a 
water  may  be  condemned  which  contains  a  very  small  amount  of  organic 
matter  while  a  Avater  highly  charged  with  impurities  of  the  worst  type 
would  be  passed  without  suspicion. 

There  are  at  present  but  two  methods  for  the  determination  of  organic 
matter  in  potable  water  which  are  worthy  of  serious  consideration. 
These  are  Frankland  and  Armstrong's  process,  and  \Vanklyn's  process. 
Frankland  and  Armstrong's  method  §  is  one  which  can  only  be  applied  in 
a  fully  appointed  laboratory,  and  which,  even  under  the  most  favorable 
conditions,  is  open  to  the  serious  objection  that,  owing  to  the  small  quan- 
tities to  be  determined  and  to  the  nature  of  the  process,  the  experimental 
error  may  represent  a  quantity  greater  than  that  of  the  substance  to  be 
determined. 

The  process  which  is  now  almost  exclusively  used  by  chemists  is 
that  first  suggested  by  Wanklyn,  Chapman,  and  Smith,  in  1867,  ||  and  is 
based  upon  the  following  reactions:  1st,  the  Nessler  test  for  ammonia; 
i.  e.y  the  production  of  a  yellow  color  by  ammonia  in  a  saturated  alka- 
line solution  of  mercuric  iodide  in  potassium  iodide;  and  2d,  the  decom- 
position of  organic  nitrogenous  substances,  with  production  of  ammonia, 

*  Report  of  Medical  Officer  of  the  Privy  Council,  1867  (10th),  p.  34. 
}  Dr.  R.  T.  Thome,  ib.,  pp.  28.  41.  \  p.  574. 

§  Journ.  Ch.  Soc.,  N.  S.,  vi.,  77. 

I  Ibid.,  v.,  448;  id.  vi.,  152,  161.  Wanklyn  :  Water  Analysis,  3d  ed.  3,  2.  Fox: 
Water  Analysis,  15. 


54  GENEKAL    MEDICAL    CHEMISTRY. 

when  they  are  boiled  with  a  highly  alkaline  solution  of  potassium  per- 
manganate. 

For  the  application  of  this  test,  the  following  solutions  are  required: 

a.  Alkaline  solution  of  potassium  permanganate,  made  by  dissolv- 
ing 200  grams  of  potassium  hydrate  ancL8  grams  of  potassium  permanga- 
nate in  a  litre  of  water;  the   solution  is  boiled   down  to   about   725  c.c., 
cooled,  and  brought  to  its  original  bulk  by  the  addition  of  the  requisite 
quantity  of  boiled  distilled  water. 

b.  N"essler  reagent. — To  prepare  this,  35   grams  of.  potassium  iodide 
and  13  grams  of  mercuric  chloride  are  dissolved  in  800  c.c.  of  water,  by 
the  aid  of  heat  and  agitation.     A    cold  saturated  solution  of  mercuric 
chloride  is  then  added,  drop  by  drop,  until  the  red  precipitate  which  is 
formed  is  no  longer  redissolved  on  agitating  the  liquid;  160  grams  of  po- 
tassium hydrate  are  then  dissolved  in  the  liquid,  to  which,  finally,  a  slight 
excess  of  mercuric  chloride  solution  is  added,  and  the  bulk  made  up  to 
one  litre  by  the  addition  of  water.     The  solution  is  then  set  aside  until 
the  red  precipitate  has  subsided,  when  the  clear,  faintly  yellowish  liquid 
is  decanted  and  preserved  in  well-stoppered  bottles,  which  should  not  be 
too  large  and  should  be  completely  filled. 

The  glass  stoppers  of  the  bottles  containing  a  and  b  should  be  well 
coated  with  paraffine,  to  prevent  adhesion. 

c.  Standard  solutions  of  ammonia. — These  are  a  stronger  and  a  weaker. 
The  first  is  made  by  dissolving  3.15  grams  of  ammonium  chloride  in  a 
litre  of  water;  the    second,    by  mixing  1  volume  of  the    first    with  90 
volumes  of  distilled  water.     The  weaker  solution,  which  contains  0.00001 
gram  (yjif  milligram)  of  ammonia  (NH3)  in  each  cubic  centimetre,  is  the 
one  which  is  used  in  examinations  of  water,  the  more   concentrated   solu- 
tion serving  simply  for  the  convenient  preparation  of  the  other. 

d.  A  saturated  solution  of  sodium  carbonate. 

e.  Distilled  water. — The  middle  third  of    the  distillate;   100  c.c.   of 
which  in  a  cylinder  should  not  be  perceptibly  colored  in  ten  minutes  by 
the  addition  of  2  c.c.  of  Nessler  reagent. 

The  testing  of  a  water  is  conducted  as  follows:  half  a  litre  of  the 
water  to  be  tested  (it  is  scarcely  necessary  to  state  that,  before  taking 
the  sample,  the  demijohn  or  other  vessel  containing  the  water  must  be 
thoroughly  shaken)  is  introduced,  by  a  funnel,  into  a  tubulated  retort 
capable  of  holding  one  litre.  If  the  water  be  acid,  which  is  rarely  the 
case,  10  c.c.  of  the  solution  of  sodium  carbonate  d  are  added.  Having 
connected  the  retort  with  a  Liebig's  condenser,  the  joint  being  made 
tight  by  a  packing  of  moistened  filter-paper,  the  water  is  made  to  boil  as 
soon  as  possible  by  applying  the  flame  of  a  Bunsen  burner,  brought  close 
to  the  bottom  of  the  naked  retort  (there  is  but  little  danger  of  fracture 
if  the  flame  do  not  reach  above  the  level  of  liquid  inside).  The  first 
50  c.c.  of  distillate  are  collected  in  a  cylindrical  vessel  of  clear  glass, 
about  an  inch  in  diameter.  The  following  150  c.c.  are  collected  and 
thrown  away,  after  which  the  fire  is  withdrawn.  While  these  are  pass- 
ing over,  the  first  50  c.c.  are  Nesslerized  (vide  infra),  and  the  result,  plus 
one-third  as  much  again,  is  the  amount  of  free  ammonia  contained  in  the 
half -litre  of  water. 

When  200  c.c.  have  distilled  o\er,  all  the  free  ammonia  has  been 
removed,  and  it  now  remains  to  decompose  the  organic  material,  arid 
determine  the  amount  of  ammonia  formed.  To  effect  this,  50  c.c.  of  the 
permanganate  solution  a  are  added  through  the  funnel  to  the  contents 
of  the  retort,  which  is  shaken,  stoppered,  and  again  heated.  The  dis- 


IMPURITIES    IN    POTABLE    WATEE.  55 

tillate  is  now  collected  in  separate  portions  of  50  c.c.  each,  in  glass  cylin- 
ders, until  three  such  portions  have  been  collected.  These  are  then 
separately  Nesslerized  as  follows:  2  c.c.  of  the  Nessler  reagent  are  added 
to  the  sample  of  50  c.c.  of  distillate;  if  ammonia  be  present,  a  yellow  or 
brown  color  will  be  produced,  dark  in  proportion  to  the  quantity  of 
ammonia  present.  Into  another  cylinder  a  given  quantity  of  the  stand- 
ard solution  of  ammonia  c  is  allowed  to  flow  from  a  burette;  enough 
water  is  added  to  make  the  bulk  up  to  50  c.c.,  and  then  2  c.c.  of  Nessler 
reagent.  This  cylinder,  and  that  containing  the  50  c.c.  of  Nesslerized 
distillate,  are  then  placed  side  by  side  upon  a  sheet  of  white  paper  and 
their  color  examined.  If  the  shade  of  color  in  the  two  cylinders  be 
exactly  the  same,  the  50  c.c.  of  distillate  contain  the  same  amount  of 
ammonia  as  the  quantity  of  standard  solution  of  ammonia  used.  If  the 
'colors  be  different  in  intensity,  another  comparison-cylinder  must  be 
arranged,  using  more  or  less  of  the  standard  solution,  as  the  first  com- 
parison-cylinder was  lighter  or  darker  than  the  distillate.  When  the 
proper  similarity  of  shades  has  been  attained,  the  number  of  cubic  centi- 
metres of  the  standard  solution  used  is  determined  by  the  reading  on  the 
burette.  This  process,  which,  with  a  little  practice,  is  neither  difficult  nor 
tedious,  is  to  be  repeated  with  the  first  50  c.c.  of  distillate  and  with  the 
three  portions  of  50  c.c.  each,  distilled  after  the  addition  of  the  perman- 
ganate solution.  If,  for  example,  it  required  1  c.c.  of  standard  solution 
in  Nesslerizing  the  first  50  c.c.,  and  for  the  others  3.5  c.c.,  1.5  c.c.,  and 
0.2  c.c.,  the  following  is  the  result  and  the  usual  method  of  recording  it: 

Free  ammonia 01    milligr. 

Correction 003  milligr. 

.013  milligr. 


Free  ammonia  per  litre 026  milligr. 

Albuminoid  ammonia 035  milligr. 

Albuminoid  ammonia 015  milligr. 

Albuminoid  ammonia 002  milligr. 

.052  milligr. 
Albuminoid  ammonia,  per  litre 104  milligr. 

Concerning  the  deductions  to  be  drawn  from  the  determination  of 
ammonia,  Mr.  Wanklyn*  says:  "  If  a  water  yield  0.00  parts  of  albuminoid 
ammonia  per  million,  it  may  be  passed  as  organically  pure,  despite  of 
much  free  ammonia  and  chlorides;  and  if,  indeed,  the  albuminoid  ammo- 
nia amount  to  .02,  or  to  less  than  0.05  part  per  million,f  the  water 
belongs  to  the  class  of  very  pure  water.  When  the  albuminoid  ammo- 
nia amounts  to  .05,  then  the  proportion  of  free  ammonia  becomes  an 
element  in  the  calculation ;  and  I  should  be  inclined  to  regard  with  some 
suspicion  a  water  yielding  a  considerable  quantity  of  free  ammonia  along 
with  .05  part  of  albuminoid  ammonia  per  million.  Free  ammonia,  how- 
ever, being  absent  or  very  small,  a  water  should  not  be  condemned  unless 
the  albuminoid  ammonia  reaches  something  like  0.10  per  million.  Albu- 


*  Water  Analysis,  3d  ed.,  51.  f  Milligrams  per  litre. 


56  GENERAL    MEDICAL    CHEMIST11Y. 

minoid  ammonia  above  0.10  per  million  begins  to  be  a  very  suspicious 
sign,  and  over  0.15  ought  to  condemn  a  water  absolutely.  The  absence 
of  chlorine,  or  the  absence  of  more  than  one  grain  of  chlorine  per  gallon, 
is  a  sign  that  the  organic  impurity  is  of  vegetable  rather  than  animal 
origin;  but  it  would  be  a  great ,  mistake^  to  allow  water  highly  contami- 
nated with  vegetable  matter  to  be  taken  for  domestic  use." 

Fifth — Nitrates. — The  existence  and  quantity  of  alkaline  nitrates  in 
water  were  formerly  regarded  as  of  much  greater  importance  than  that 
now  accorded.  They  were  considered  as  indicating,  if  not  the  actual  sew- 
age present,  at  least  the  amount  of  previous  contamination,  for  the  rea- 
son that  they  are  the  principal  ultimate  products  of  the  oxidation  of 
nitrogen  contained  in  organic  substances.  They  exist,  however,  also  in 
waters  perfectly  free  from  organic  contamination  as  well  as  in  rain-water, 
being  taken  up  by  the  former  in  its  passage  through  certain  geological 
strata,  and  being  formed  in  the  latter  probably  by  direct  union  of  the 
nitrogen  and  oxygen  of  the  air. 

Sixth — Poisonous  metals. — The  metals  most  liable  to  occur  in  potable 
waters  are  iron,  copper,  and  lead. 

a.  Iron  may  be  dissolved  by  water  either  during  its  passage  through 
ferruginous  strata  in  the  earth,  or  by  conduction  through  iron  pipes.  Cer- 
tain ferruginous  waters  are  valuable  medicinal  agents,  and  may  contain 
as  much  as  607  milligrams  of  salts  of  iron  to  the  litre.  For  ordinary  uses, 
however,  a  water  should  not  contain  more  than  three  milligrams  per  litre 
of  iron.  The  amount  of  iron  dissolved  by  water  in  passing  through  iron 
pipes  is  exceedingly  small.  The  distribution  of  water  in  large  cities,  and 
frequently  the  main  supply  also,  is  through  such  channels. 

Mr.  A.  W.  Blyth  has  also  shown  that  water  containing  organic  mat- 
ter is  purified,  to  a  large  extent,  of  these  contaminations  by  passage 
through  iron  pipes. 

y8.  Copper. — Drinking-water  is  not  liable  to  become  'contaminated 
with  the  salts  of  this  element  except  when  it  comes  in  contact  with  deposits 
of  the  metal,  or  of  its  ores  in  its  passage  through  the  earth.  The  experi- 
ments of  Muir  have  shown  that  pure  water  would  not  dissolve  copper,  but 
that  water  containing  carbon  dioxide,  especially  when  also  containing  cal- 
cium chloride  and  ammonium  nitrate,  would  dissolve  it  in  considerable 
quantity. 

Y.  Lead. — The  most  serious,  as  well  as  the  most  common  metallic 
contamination  of  water,  is  that  with  lead.  Although  a  water  contain  a 
very  small  quantity  of  lead  salts,  there  is  no  doubt  that  its  continued  use 
will  produce  well-marked  cases  of  chronic  lead-poisoning,  and  numerous 
instances  are  recorded  in  which  the  disorder  has  been  traced  directly  to 
this  cause,  and  has  ceased  with  its  removal. 

The  power  possessed  by  a  water  of  dissolving  lead  varies  materially 
with  the  nature  of  the  substances  which  it  holds  in  solution.  The  pres- 
ence of  nitrates  is  favorable  to  the  solution  of  lead,  an  influence  which  is, 
however,  much  diminished  by  the  simultaneous  presence  of  other  salts.  A 
water  highly  charged  with  oxygen  dissolves  lead  readily,  especially  if  the 
metallic  surface  be  so  exposed  to  the  action  of  the  water  as  to  be  alter- 
nately acted  upon  by  it  and  by  the  air.  On  the  other  hand,  waters 
containing  carbonates  or  free  carbonic  acid  may  be  left  in  contact  with 
lead  with  comparative  impunity,  owing  to  the  formation  of  a  protective 
coating  of  the  insoluble  carbonate  of  lead  on  the  surface  of  the  metal. 
This  does  not  apply,  however,  to  water  charged  with  a  large  excess  of 
carbon  dioxide  under  pressure.  It  will  be  observed  from  what  precedes 


IMPURITIES    IN    POTABLE    WATER.  57 

that  of  all  natural  waters  that  most  liable  to  contamination  with  lead  is 
rain-water;  it  contains  ammonium  nitrate  with  very  small  quantities  of 
other  salts;  and  it  is  highly  aerated,  but  contains  no  carbonates  and  com- 
paratively small  quantities  of  carbon  dioxide.  Obviously,  therefor,  rain- 
water should  neither  be  collected  from  a  leaden  roof,  nor  stored  in  leaden 
tanks,  nor  drank  after  having  been  long  in  contact  with  lead  pipes.  As  a 
rule,  the  purer  the  water  the  more  liable  it  is  to  dissolve  lead  when  brought 
in  contact  with  that  metal,  especially  if  the  contact  occur  when  the  water 
is  at  a  high  temperature,  or  when  it  lasts  for  a  long  period. 

It  has  been  proposed,  in  order  to  avoid  the  solution  of  lead,  to  use 
pipes  of  lead  coated  internally  with  block  tin.  Unfortunately,  however, 
it  has  been  found  that  wherever  a  fault  occurred  in  the  coating,  the  lead 
is  dissolved  much  more  rapidly  than  from  pipes  made  entirely  of  lead. 
Moreover,  tin  is  a  substance  which  is  by  no  means  insoluble  in  water, 
its  solubility  being  materially  increased  when  it  is  alloyed  with  even  a 
very  small  proportion  of  lead. 

To  determine  the  power  of  water  for  dissolving  lead,  take  two  tum- 
blers of  the  water  to  be  tested  ;  in  one  place  a  piece  of  lead,  whose 
surface  has  been  scraped  bright,  and  allow  them  to  stand  twenty-four 
hours.  At  the  end  of  that  time  remove  the  lead  and  pass  sulphuretted  hy- 
drogen through  the  water  in  both  tumblers  ;  if  the  one  which  contained 
the  metal  become  perceptibly  darker  than  the  other,  the  water  has  a 
power  of  dissolving  lead  such  as  to  render  its  contact  with  surfaces  of 
that  metal  dangerous  if  prolonged  beyond  a  short  time. 

The  testing  of  water  for  poisonous  metals  is  a  very  simple  matter,  and 
consists  in  adding  to  the  water,  in  a  porcelain  capsule,  some  solution  of 
ammonium  sulphydrate.  If  the  water  become  perceptibly  darker  after 
the  addition  of  the  reagent,  it  contains  a  poisonous  metal,  whose  nature 
is  then  to  be  determined.  Having  determined  whether  the  metal  is  iron, 
copper,  or  lead,  a  quantitative  determination  may  be  made  by  imitating 
the  shade  of  color  produced  by  ammonium  sulphydrate  in  a  given  bulk  of 
the  water,  with  a  standard  solution  of  a  salt  of  the  corresponding  metal 
and  ammonium  sulphydrate;  the  volume  of  the  standard  solution  used 
containing  the  same  amount  of  the  metal  as  the  volume  of  water  tested.  The 
standard  solutions  are  the  following  :  for  iron,  4.96  grams  of  ferrous  sul- 
phate dissolved  in  1  litre  of  water  ;  each  cubic  centimetre  contains  0.001 
gram  iron.  For  copper,  3.93  grams  of  cupric  sulphate  dissolved  in  1  litre 
of  water  ;  each  cubic  centimetre  contains  0.001  gram  copper.  For  lead, 
1.66  gram  of  lead  acetate  in  1  litre  of  water;  each  cubic  centimetre  con- 
tains 0.001  gram  lead. 

Seventh — Suspended  solids. — Most  natural  waters  deposit,  on  standing, 
more  or  less  solid  insoluble  material.  These  substances  have  been  either 
suspended  mechanically  in  the  water,  which  deposits  them  when  it  re- 
mains at  rest,  or  they  have  been  in  solution  and  are  deposited  by  becom- 
ing insoluble  as  the  water  is  deprived  of  carbon  dioxide  by  exposure  to 
air  and  by  relief  from  pressure. 

The  suspended  particles  should  be  collected  by  subsidence  in  a  conical 
glass,  and  should  be  examined  microscopically  for  low  forms  of  animal 
and  vegetable  life.  The  quantity  of  suspended  solids  is  determined  by 
passing  a  litre  of  the  turbid  water  through  a  dried  and  weighed  filter, 
which,  with  the  collected  deposit,  is  again  dried  and  weighed.  The  dif- 
ference between  the  two  weights  is  the  weight  of  suspended  matter  in  a 
litre  of  the  water. 

Purification  of  water. — The  artificial  means  of  rendering  a  more  or 


58  GENERAL    MEDICAL    CHEMISTRY. 

less  Contaminated  water  fit  for  use  are  of  five  kinds  :  1.  Distillation; 
2.  Subsidence;  3.  Filtration;  4.  Precipitation;  5.  Boiling. 

The  method  by  distillation  is  used  in  the  laboratory  when  a  very  pure 
water  is  desired,  and  also  at  sea  upon  steamships,  and  even  on  sailing 
vessels  upon  occasion.  Distilled  water  is,  however,  too  pure  for  continued 
use,  being  hard  of  digestion,  and  flat  to  the  taste  from  the  absence  of 
gases  and  of  solid  matter  in  solution.  When  circumstances  oblige  the 
use  of  such  water,  it  should  be  agitated  with  air,  and  should  be  charged 
with  inorganic  matter  to  the  extent  of  about  0.15  gram  each  of  calcic 
bicarbonate  and  sodium  chloride  to  the  litre. 

Purification  by  subsidence  is  adopted  only  as  an  adjunct  to  precipita- 
tion and  filtration,  and  for  the  separation  of  the  heavier  particles  of  sus- 
pended matter. 

The  ideal  process  of  filtration  consists  in  the  separation  of  all  particles 
of  suspended  matter,  without  any  alteration  of  such  substances  as  are 
held  in  solution.  In  the  filtration  of  potable  waters  on  a  large  scale, 
however,  the  more  minute  particles  of  suspended  matters  are  only  par- 
tially separated,  while,  on  the  other  hand,  an  important  change  in  the  dis- 
solved materials  takes  place,  at  least  in  certain  kinds  of  filters,  in  the  oxi- 
dation of  organic  matters,  whether  in  solution  or  in  suspension.  In  the 
filtration  of  large  quantities  of  water  it  is  passed  through  sand  or  char- 
coal, or  through  both  substances  arranged  in  alternate  layers.  Filtration 
through  charcoal  is  much  more  effective  than  that  through  sand,  owing 
to  the  much  greater  activity  of  the  oxidation  of  nitrogenized  organic 
matter  in  the  former  case. 

Precipitation  processes  are  only'  adapted  to  hard  waters,  and  are  de- 
signed to  separate  the  excess  of  calcium  salt,  and  at  the  same  time  a  con- 
siderable quantity  of  organic  matter,  which  is  mechanically  carried  down 
with  the  precipitate.  The  method  usually  followed  consists  in  the  addi- 
tion of  lime  (in  the  form  of  lime-water),  in  just  sufficient  quantity  to 
neutralize  the  excess  of  carbon  dioxide  present  in  the  water.  The  added 
lime,  together  with  the  calcium  salt  naturally  present  in  the  water,  is 
then  precipitated,  except  that  small  portion  of  calcium  carbonate  which 
the  water,  freed  of  carbon  dioxide,  is  capable  of  dissolving.  To  deter- 
mine when  sufficient  lime-water  has  been  added,  take  a  sample  from  time 
to  time  during  the  addition,  and  test  it  with  solution  of  silver  nitrate 
until  a  brown  precipitate  is  formed.  At  this  point  cease  the  addition  of 
lime-water  and  mix  the  limed  water  with  further*  portions  of  the  hard 
water,  until  a  sample,  treated  with  silver-nitrate  solution,  gives  a  yellowish 
in  place  of  a  brown  color.  The  purification  of  water  by  boiling  can  only 
be  carried  on  upon  a  small  scale  ;  it  is,  however,  of  great  value  for  the 
softening  of  temporarily  hard  waters,  and  for  the  destruction  of  organized 
impurities,  for  which  latter  purpose  it  should  never  be  neglected  during 
outbreaks  of  cholera  and  typhoid,  if,  indeed,  water  be  drank  at  all  at 
such  times. 


Mineral  Waters. 

Under  this  head  are  classed  waters  charged  to  such  an  extent  with  dis- 
solved substances,  or  having  a  temperature  such  as  to  render  them  avail- 
able for  therapeutical  uses.  As  a  rule,  spring-water  has  a  temperature 
less  than  15°,  but  there  are  many  springs  whose  waters  are  much  warmer. 
When  their  temperature  is  higher  than  20°  they  are  known  as  thermal 


MINERAL    WATERS.  59" 

springs,  and  are  frequently  of  therapeutical  value  independently  of  the 
nature  of  their  dissolved  solids,  which  is  exceedingly  various.  Among 
the  most  noted  thermal  springs  are  those  of  Wildbad,  35.5°  ;  Warmbrunn, 
38°  ;  Toplitz,  49°  ;  Buxton,  28°  ;  Clifton,  30°  ;  Chaudes-Aigues,  81°  ; 
Ems,  46°  ;  Carlsbad,  73°  ;  Arkansas  Hot  Springs  from  40.5°  to  66°  ;  Vir- 
ginia Hot  Springs,  37.8°  to  41°.  The  water  of  the  great  Geyser  in  Ice- 
land has  a  temperature  of  over  100°  in  the  centre. 

The  composition  of  mineral  waters  varies  greatly,  according  to  the 
nature  of  the  strata  or  veins  through  which  the  water  passes,  and  to  the 
conditions  of  pressure  and  previous  composition  under  which  it  is  in  con- 
tact with  these  deposits.  Waters  of  very  different  composition  in  some 
localities  come  to  the  surface  in  close  proximity  to  each  other,  as  at 
Saratoga  Springs,  where  the  Congress  and  Columbian  springs,  differing 
widely  from  each  other  in  their  chemical  and  therapeutical  properties,, 
are  only  a  few  rods  apart. 

The  substances  almost  universally  present  in  mineral  waters  are: 
oxygen,  nitrogen,  carbon  dioxide,  sodium  carbonate,  bicarbonate,  sul- 
phate and  chloride,  calcium  carbonate  and  bicarbonate.  Of  substances- 
occasionally  present  the  most  important  are:  sulphydric  acid,  sulphides 
of  sodium,  iron  and  magnesium,  bromides  and  iodides  of  sodium  and 
magnesium,  calcium  and  magnesium  chlorides,  carbonate,  bicarbonate,, 
sulphate,  peroxide  and  crenate  of  iron,  silicates  of  sodium,  calcium,  mag- 
nesium and  iron,  aluminium  salts,  salts  of  lithium,  caesium  and  rubidium,, 
free  sulphuric,  silicic,  arsenic  and  boric  acids,  and  ammoniacal  salts. 

Although  a  sharply  defined  classification  of  mineral  waters  is  not  pos- 
sible, one  which  is  useful,  if  not  accurate,  may  be  made,  based  upon  the 
predominance  of  some  constituent  or  constituents  which  impart  to  the 
water  a  well-defined  therapeutic  value.  A  classification  which  has  been 
generally  adopted  is  into  five  classes: 

First — Acidulous  waters,  those  whose  value  depends  upon  the  pres- 
ence of  carbon  dioxide. 

Second — Alkaline  waters,  those  containing  a  notable  proportion  of 
carbonates,  or  bicarbonates  of  sodium,  potassium,  or  lithium. 

Third —  Chalybeate  waters,  those  charged  with  compounds  of  iron. 

Fourth — Saline  waters,  those  containing  neutral  salts  in  considerable 
quantity. 

Fifth — Sulphurous  waters,  those  holding  hydrogen  sulphide,  or  a 
metallic  sulphide  in  solution. 

Besides  those  waters  which  may  be  classed  under  one  of  the  above 
heads,  there  are  others  which,  containing  some  active  substance  not 
usually  present  in  natural  waters,  such  as  alum,  free  sulphuric  acid,  or 
arsenical  compounds,  may  for  the  present  be  placed  in  a  sixth  class. 

Acidulous  icaters. — These  waters,  of  which  the  artificially  prepared 
carbonic  water,  or  soda-water,  may  be  considered  the  type,  contain  but 
small  quantities  of  solid  matters  in  solution,  the  most  abundant  being 
the  bicarbonates  of  sodium  and  of  calcium,  and  sodium  chloride.  They 
are  always  cool,  fresh,  and  sparkling,  owing  to  the  presence  in  them  of 
carbon  dioxide  in  considerable  quantity,  and  to  the  absence  of  hydrogen 
or  other  sulphides. 

Alkaline  waters. — The  temperature  of  waters  of  this  class  is  usually 
above  20°,  although  some  are  cooler.  They  are  alkaline  in  reaction, 
some  sufficiently  so  to  have  a  soapy  taste,  others  only  after  expulsion  of 
the  free  carbon  dioxide,  which  they  contain  in  very  variable  proportion. 
Their  principal  solid  constituents  are  the  bicarbonates  of  sodium,  calcium, 


60  GENERAL    MEDICAL    CHEMISTRY. 

magnesium,  and  sometimes  lithium.  Their  tenure  in  sodium  chloride  is 
usually  less  than  that  of  the  acidulous  waters. 

Chalybeate  waters. — Iron,  being  widely  distributed  in  nature,  is  con- 
tained in  most  natural  waters,  fresh  or  mineral.  When  the  quantity  of 
iron  salts  exceeds  forty  milligrams  per  litre,  the  water  may  be  considered 
as  having  medicinal  value.  Chalybeate  waters  are  usually  coo],  some- 
times warm,  have  a  ferruginous  taste,  and  are  clear  as  they  emerge  from 
the  earth.  Those  containing  iron  in  the  form  of  its  bicarbonate  become 
turbid  and  deposit  a  brownish  yellow  sediment  on  exposure  to  air,  the 
bicarbonate  being  decomposed  and  carbon  dioxide  given  off.  Besides 
ferrous  bicarbonate,  many  of  the  waters  of  this  class  contain  ferrous  sul- 
phate, crenate  and  apocrenate,  calcium  carbonate,  sulphates  of  potassium, 
sodium,  calcium,  magnesium,  and  aluminium,  notable  quantities  of  sodium 
chloride,  and  sometimes  arsenical  compounds. 

Saline  waters. — The  solid  constituents  of  waters  of  this  class  are  so 
diverse  in  kind  that  the  group  may  well  be  divided  in  subgroups. 

a.  Chlorine  waters  are  such  as  contain  large  quantities  of  sodium 
chloride,  associated  with  less  amounts  of  the  chlorides  of  potassium,  cal- 
cium, and  magnesium.  Some  of  these  are  so  rich  in  sodium  chloride  that 
they  are  not  of  service  as  therapeutic  agents,  but  are  evaporated  either 
by  solar  or  artificial  heat,  to  yield  a  more  or  less  pure  salt.  Any  natural 
water  containing  more  than  3  grams  per  litre  of  sodium  chloride  belongs 
to  this  class,  provided  it  do  not  contain  substances  more  active  in  their 
medicinal  action  in  such  proportion  as  to  warrant  its  classification  else- 
where. Waters  containing  more  than  15  grams  per  litre  are  too  concen- 
trated for  internal  administration.  They  are  usually  cool,  and  have  a  salt, 
but  not  a  bitter  taste.  Some  of  them  are  highly  charged  with  carbon 
dioxide,  and  in  some  instances  the  pressure  under  which  they  are  dis- 
charged from  the  earth  is  sufficient  to  project  them  to  a  height  of  over 
thirty  feet.  They  contain  also  traces  of  iodides  and  bromides,  and  bicar- 
bonates  of  sodium  and  calcium. 

fi.  Sulphate  waters  are  actively  purgative  from  the  presence  of  consid- 
erable proportions  of  the  sulphates  of  sodium,  calcium,  and  magnesium. 
Some  contain  large  quantities  of  sodium  sulphate,  with  mere  traces  of  the 
calcium  and  magnesium  salts,  while  in  others  the  proportion  of  the  sul- 
phates of  magnesium  and  calcium  is  as  high  as  30  grams  per  litre,  to  20 
grams  per  litre  of  sodium  sulphate.  They  vary  much  in  concentration; 
from  5  grams  of  total  solids  to  the  litre  in  some,  to  near  60  grams  per  litre 
in  others.  They  have  a  salty,  bitter  taste,  and  vary  much  in  temperature. 

y.  Bromine  and  iodine  ivaters  are  such  as  contain  the  bromides  or 
iodides  of  potassium,  sodium,  or  magnesium  in  sufficient  quantity  to  com- 
municate to  them  the  medicinal  properties  of  those  salts.  An  exagge- 
rated type  of  this  class  is  to  be  found  in  the  water  of  the  Dead  Sea, 
which  contains  a  large  proportion  of  magnesium  bromide.  The  mineral 
waters  of  Pomeroy,  O.,  are  worked  as  a  source  of  bromine. 

Sulphurous  waters. — The  waters  of  this  class  are  distinguished  by 
the  presence  of  hydrogen  sulphide  or  of  the  sulphides  of  the  alkaline 
metals — usually  of  both.  Their  temperature  varies  much  in  different 
waters,  but  is  usually  high.  They  have  the  disagreeable  odor  of  hydrogen 
sulphide,  and  form  a  black  mixture  with  a  solution  of  a  lead  salt.  The 
fixed  salts  which  they  hold  in  solution  are  principally  sodium  chloride, 
sulphate,  and  bicarbonate,  and  calcium  bicarbonate.  The  proportion 
of  total  solids  varies  in  different  waters  of  this  class  from  0.2  to  4  grams 
per  litre. 


MINERAL    WATEKS. 


61 


COMPOSITION  OF  MINERAL  WATERS. 

QUANTITIES   IN   MILLIGRAMS   PER   LITRE. 


1. 

2. 

3. 

4.        5. 

6. 

7. 

8. 

9, 

10. 

% 

.g 

1 

Condillac. 

Wilhelras  Quelle. 

Apollinaris. 

1 
fl 

jhy 
Grande  Grille). 

j 

I 

ll 

II 

> 

P 

> 

5 

Temperature 

17.5° 
1.0034 
4070 
1035 
979 

11° 
1.0018 
2091 
1946 
957 

13°    |  13.5°'  18.5° 

10.5° 
1.0031 
4345 
2458 
1049 
59 

41.8° 

30.8° 

Density               .... 

Total  solids  
Carbon  dioxide.  .  .  . 
Sodium  bicarbonate 
Potassium 
Lithium 
Calcium 
Strontium 
Barium 
Magnesium 
Ferrous 
Manganous 
Sodium  chloride.  .  . 
Potassium  "       ... 

2193     2457 
1083     2249 
166         84  1257* 

7006     7i55 
908     1067 
4883     5029 
352!       440 

7195 
1049 
5103 
315 

240 
12.6 
11 
1.3 

'551 

traces. 

20 
431 

1359 

3 

677 

3 

59* 

577 

434 
3 

570 
5 

462 
5 

38 

209 
30 

313 

35 

167 
5 
2 
1690 
37 

442* 


405 
4 

303       200       328 
4           4:          4 
traces,  traces,  traces. 
534       518       534 

6.7 
6.'7 

2040 
1 

71 

150 

466 

1267 

.... 

Calcium       " 

Magnesium  chloride 
Sodium  sulphate  .  . 

150 

23 

148 

175 

"23 

300 

972 

291 

291 

291 

92.7 

.  .  .  . 

Calcium         u 
Sodium  phosphate. 
Potassium       '  ' 
Calcium 
Aluminium     '  ' 

"46 



53 

1     

! 

|     

1 

130 

46 

91 



r 

, 

traces. 

i               j 

Sodium  bromide.  .  . 
Potassium     '  ' 

traces. 

1 

j 

I 

Alumina  ) 

50 
traces. 

j  ... 

Silex  f 

I     63 



101 

8!        16 

70         50;        60  1 
braces,  traces,  traces. 

traces. 

Organic  matter.  .  .  . 
Ferrous  sulphate  .  . 

j 

10 

1      . 

1 

d 

P, 

S 

a 

1 
d 

1 

3 

1 

Bouquet. 

i 

..j 
1 
1 

!  Jutier  and 
Lefort. 

*  Calculated  as  carbonates  instead  of  bicarbonates. 

(1.)  Sodium  and  calcium  crenates,  traces.  (2.)  Sodium  borate,  65.  (3.)  Silicates  of 
calcium  and  of  aluminium,  245.  (4.)  Oxide  of  iron,  20.  (5.)  Alumina,  strontia,  lithia, 
organic  matter— traces.  (7,  8,  and  9.)  Sodium  arsenate,  2;  sodium  borate,  traces.  (10.) 
Calcium  fluoride,  9.2;  sodium  silicate,  57  ;  lithium  silicate,  traces;  baregine,  traces. 


62 


GENERAL    MEDICAL    CHEMISTRY. 


COMPOSITION  OF  MINERAL  WATERS—  Continued. 


11. 

12, 

13. 

14. 

15. 

16. 

17. 

18. 

19. 

20. 

Ems 
(  Furstenbrannen). 

j 

Buffalo  (Lithia). 

Gettysburg. 

Ballston(Artesian). 

Ballston 
(Sans  Souci). 

Glen  Flora,  Wis. 

j 

Cheltenham 
(Royal  Old  Well). 

d 

M 

35.3°    46.3° 
1.0031  1.0031 
3543  ;     3518 
902       884 
2032     1979 

11.1° 
1.0159 
21138 
3627 
204 

10° 

1.015 
16906 

4580 
82 

Density       

Total  solids.  

i     1405 
417 

'606 
32 
214 

!     3803 
'658 

606 

612      .... 

4628 
19 

Carbon  dioxide  .... 
Sodium  bicarbonate 
Potassium      4 
.Lithium          ' 
Calcium 
Strontium      4 
Barium 
Magnesium    4 
Ferrous 
Manganous     4 
Sodium  chloride.  .  . 
Potassium     4< 

111 

22 

traces. 
233 
0.28 

traces. 
236 
0.48 

1157 

133       202 
4082     3311 
15  traces. 
67         31 
3096     3104 
27       158 

267 

292 

243* 

179* 

25| 
1086 
4.3      .... 

200 
2.6 
0.8 
984 

187 
3.6 
0.6 
1012 

190 
2 

212 
1 

97* 

6.5* 
10.3* 

70 

traces. 

12855 
570 

9809 
97 

3 

20 

3420 

3089 
133 
43 
794 
312 

Lithium         4t      ... 

Magnesium  44      ... 

! 

114 
1354 

Sodium  sulphate.  .  . 
Potassium     ;  '      ... 
Magnesium  u      ... 

2.2 

39 

0.8 
51 

32 

9 

8 

12  7 



9 

Calcium         "      ... 
Sodium  phosphate.. 
Potassium      '  ' 
Calcium         u 
Aluminium    4< 
Sodium  iodide  



472;      760 

1 

.... 

—  .  traces. 

traces. 

54 

6.4 
braces. 

0.1 
traces. 

2 

11 

74 

Sodium  bromide.  .  . 

62         18 

10.7 

Alumina  

1.3  trace. 
13         20 
braces.  |     .... 

4 
16 
2 

2 
11 
34 

traces. 
1 

Silex  

27 
traces. 

143 

38 

257 

Organic  matter.  .  .  . 

! 

1 

- 

i 

£ 

1 

i 

1          S 

1  |  I 

f 

o 

If 

11 

*  Calculated  as  carbonates  instead  of  bicarbonates. 
(13.)  Aluminium  sulphate,  129;   phosphoric  acid  and  iodine,  traces, 
chloride,  trace.     (20.)  Ammonium  chloride,  trace  ;  peroxide  of  iron,  15. 


(16.)   Rubidium 


MINEKAL    WATERS. 


COMPOSITION  OF  MINERAL  WATERS—  Continued. 


21.   22.   23. 


i! 

|S 


10° 


10C 


1.0015  1  012 


14175 
2810 


14681 
2399 


1431*,  1275* 


262* 
60*  i 

10306 


1010 
1014 
49.6 


6* 

51* 

10997 

287 

1238 

781 


ii' 

1.0073 
8735 
1632 


1061 


traces,  traces. 


traces,  traces. 


41 


!  traces. 
16 


17* 

31.6* 

traces. 

5882 
287 
200 


303 


587 
389 


24. 


25.      26. 


27.      28. 


29. 


30. 


!  ill    ! 


7.8C 


7603 

3340i 

184i 


11662 

2914 

155 


1.009 
151281 

3252 

74! 


Temperature. 


1.011      j    |     iDeusity. 


16995 
3865 
1223 


8823 
2127 

257* 


837 


82    36   196! 

2458|  1880!  2925 

traces,  traces,  traces. 

16J   1.3    30| 

2085;   736  3025 

6'    14    29 


66  Total  solids. 
..j Carbon  dioxide. 
2*j Sodium  bicarbonate 
.J  Potassium      " 
. . .  traces.  Lithium 
266       23*  Calcium 

Strontium      " 


6864! 
188 


8684 

74 ! 


8741 
165 


154      .    . 
2886  1319* 
7i     .... 

35,     ....I     Barium 

2560     554*1       296         5*  Magnesium    " 
17       55*  2  traces.  |  Ferrous 

I     ....       ....  JManganous     " 

•9634     4953!        32,          8  Sodium  chloride. 

422      traces.  I     ...   i  Potassium 

.  .j Lithium 

, .  :Calcium 

. .  JMagnesium 

,  .j Sodium  sulphate. 

!  3  Potassium 

j     ....  Magnesium 

127J     ....  Calcium 

. ;     i     .  Sodium   phosphate. 

....'      .  j     .Potassium        •' 

5.6J      !      ;  i          ..jCalcium 


15 


47 


0.3        0.4  traces. 


traces. 


99 


traces, 
traces. 


8.4 


2.4       0.1:      3.41      4.3 


147       4.6 


73 


traces,  traces.! 


13 


14 


7.2  2. 2  traces. 
20;  22j  11 
. .  traces,  traces. 


traces,  j 


. .  j     .... : Aluminium      " 
. .  I     .  , . .  j  Sodium  iodide. 
. .  I     ....Potassium" 
. .  j     ....  Sodium  bromide. 
. .  •     ....  Potassium     ' ' 

4  traces.  Alumina. 

6,        18,Silex. 

3  5  Organic  matter. 

. .  j     ....  | Ferrous  sulphate. 
.  Ferrous  crenate. 


*  Calculated  as  carbonates  instead  of  bicarbonates. 

(23.)  Strontium  sulphate,  sodium  borate,  calcium  fluoride,  traces;  sodium  nitrate,  9.3; 
ammonia,  0.9.  (24.)  Calcium  fluoride  and  sodium  borate,  traces.  (25.)  Calcium  fluoride 
and  sodium  borate,  traces.  (26.)  Calcium  fluoride  and  sodium  borate,  traces.  (27.)  Cal- 
cium fluoride  and  sodium  borate,  traces.  (28.)  Potassium  silicate,  120  ;  sodium  silicate, 
€9  ;  strontium  sulphate,  trace.  (30.)  Calcium  fluoride  and  lithia,  traces. 


GENERAL    MEDICAL    CHEMISTRY. 


COMPOSITION  OF  MINERAL  WATERS— Continued. 


31.      32. 

33.      34. 

35. 

36.      37. 

38. 

39. 

40. 

«j 

-£ 

1 

1 

' 

1 

if 

1     1 

I 

1-3 

. 

a 

3 

i 

i 

*          -n 

..-- 

1 

8 

g 

if 

J 

s 

•ffi 

c»  ~-^ 

1     1     I 

2 

1 

It 

O             ;         S                            &                        f^ 

W          02          w         H            m 

Temperature 

73°        12 
1.0047    1.007 
5459     8653 

788      .... 
1262      1154 

1  57  5° 

Density       .  .  .  ;  . 

32440   25294 
807       402 

1.05241.0031 
57681!  44879 

1.0118 
14940 

i 

Total  solids  
Carbon  dioxide.  .  .  . 
Sodium  bicarbonate 
Potassium       k 
Lithium 
Calcium 
Strontium      ' 
Barium 
Magnesium    ' 
Ferrous           ' 
Manganous     ' 
Sodium  chloride.  .  . 
Potassium     '  * 

4710 
9 
506* 

4943      7471 
:      .... 

434*;  1166*      .... 

2844*       .... 

6.3 
300        3.6 
:       1.7 

• 

18*      .... 
344*        98* 

100          15      700*|     ....;       505 

51* 

i                                       ! 

i             1 

463 
....      45.3 
....           5 

1038      1454 

834       520  ; 
i     153*! 

1408 
12 

25* 

57*      
39*      .... 

....      7956      2314      1676 

11612 
233 

28 
57 
1011 

3928 

458     5771 
110      

Lithium         " 

Calcium         '  ' 

Magnesium  tk      .  .  .  !      .  .  .         .... 
Sodium  sulphate.  ..'     2587     4750 
Potassium     "                                 65 

2260     3939 
16120     6056 
625        198 
12121      5150 
338     1346 

20828    17927 
67       158 
25037    22422 
6676      1512 

381 

48 

459        129 

Magnesium  " 

Calcium         "      ... 
Sodium  phosphate.. 
Potassium      '  ' 
Calcium          '  ' 
Aluminium    " 
Sodium  iodide..  .  . 

1 
3 

.  .  .  .  !       879 

i 

13  2             i 

0.22       2.4 
0.32|       7.1 

i 

23      .... 
60      

4;       98 

Potassium  "     

I 

Sodium  bromide.  .  . 

....  !  traces 

7      .... 

14         32 

....:        64 

Potassium     " 

Alumina 

}  ™  j  traces. 
f  2d  1  traces. 
....  traces. 

27           4 
151          12 

10 
23 
traces. 

29 

Silex  

75      .... 

13 
traces. 

330       120 
95      .... 

Organic  matter.  .  .  . 

Ferrous  sulphate 

1 

Ferrous  crenate.    .  . 

i            !            < 

i 

i 

a?                    oo 

.2           .2 

1   ,  1 

«                bb 

>            9 

g          -8 

&       a 

^ 

| 

H              P 

Chandler 
,  and  Cairns. 

I 

i     l| 
1     II 

p*       a 

*  Calculated  as  carbonates  instead  of  bicarbonates. 

(31.)  Calcium  fluoride,  3.2;  ferric  oxide,  3.6;  manganese  oxide,  0.8;  magnesia,  179; 
strontia,  0.96.  (32.)  Calcium  fluoride,  traces.  (33.)  Lithium  sulphate,  0.4;  strontium 
sulphate,  2.8;  barium  sulphate,  0.1.  (34.)  Magnesium  bromide,  11.  (38.)  Peroxide  of 
iron,  8. 


MINERAL    WATERS. 


65 


COMPOSITION  OF  MINERAL  WATERS—  Continued. 


41. 

42. 

43. 

44. 

45. 

46. 

47. 

4. 

49. 

50. 

Schwalbach. 

! 

1 

£ 

i 

Saratoga 
(Columbian). 

Homburg 
(Stahlbrunnen). 

j 

1 

"3 
O 

Bedford  (Alum). 

Eockbridge 
(Alum). 

10  4° 

Temperature. 
Density. 
Total  solids. 
Carbon  dioxide. 
Sodium  bicarbonate 
Potassium      * 
Lithium          ' 
Calcium 
Strontium      ' 
Barium 
Magnesium    l 
Ferrous           " 
Manganoua     "• 
Sodium  chloride. 
Potassium     '  ' 
Lithium         " 
Calcium         " 
Magnesium  u 
Sodium  sulphate. 
Potassium     '  ' 
Magnesium  " 
Calcium         u 
Sodium  phosphate. 
Potassium      u 
Calcium         " 
Aluminium    u 
Sodium  iodide. 
Potassium  ** 
Sodium  bromide. 
Potassium     '* 
Alumina. 
Silex. 
Organic  matter. 
Ferrous  sulphate. 
Ferrous  crenate. 

*849 
2471 

1.0007 
603 
1920 
20  6 

1.0073 

270'    5446 
445  traces. 

6981 
2316 
264 

14989 

2944 

4156 

1215 

801 
38 

602* 

221 

1166* 

1076* 

855* 

159* 

74* 
128* 
traces. 
6 

212 

84 
18.4 

7 

76 



801 
96* 

146* 

46* 

70* 

7* 

66* 





.... 

12 

358 

4576 

11404 

2262 

3 

7 

1523 
781 

'lei 

306 
6 
385 
1031 

735 
484 

"is 

12 
216 
86 

"l9 
25 

3 

6 



7.8 
3.7 

25 

597 
2344 

21 

traces. 

40 



21 

5 

407 

"35 

.... 

2 

i 

•aces. 
4 

"32 

traces. 

33 

252 

35 

45 

71 

20 

40 

428 

29 
5 
11 

.... 

traces. 
607 

98 

Poggiale. 

4 

3 

°2 

1 
d 

111 

ft      M 

to 

I 

A 

3 

Struvc. 

B 

Hardin. 

A.  A.  Hayes 

*  Calculated  as  carbonates  instead  of  bicarbonates. 

&)  Crenates  of  sodium  and  potassium,  2.  (44.)  Alum,  407.  (49.)  Sulphates  of 
spper,  zinc,  cobalt,  and  nickel,  4.11;  ferric  sulphate,  330;  aluminium  sulphate,  414 ; 
langanese  sulphate,  329;  lithium  sulphate,  4.14;  sulphuric  acid  (free),  68.85 ;  magne- 
ium  and  ammonium  nitrates,  8.82. 


66 


GENERAL    MEDICAL    CHEMISTRY. 


COMPOSITION  OF  MINERAL  WATERS— Continued. 


51. 

52. 

53. 

54. 

55. 

56. 

57, 

58. 

59. 

60. 

Bagneres  (Bayen). 

e 

> 

Aix-ln-Chapelle 
(Cornelius). 

Aix-la-Chapelle 
(Empereur). 

Aix  (Savoy). 

Massena 
(St.  Regis). 

Roanoke 
(Red  Sulphur). 

6\ 

White  Sulphur, 
Virginia. 

Red  Sulphur, 
Virginia. 

68° 

— 

45.4° 

55° 

45° 

48° 

'465 
54 

i.osi? 

3404 

1.0065 

2578 

1.0025 
2314 
92 

Total  solids 

227 

267 

3730 

4102 

430 

26 

372 

Carbon  dioxide.  .  .  . 

Sodium  bicarbonate 
Potassium      " 
Lithium 
Calcium 
Strontium      " 
Barium 
Magnesium    " 
Ferrous 
Manganous     " 
Sodium  chloride.  .  . 
Potassium     " 
Lithium        " 
Calcium         " 
Magnesium  " 
Sodium  sulphate.  .  . 
Potassium     4t 
Magnesium  " 
Calcium         " 
Sodium  phosphate.. 
Potassium     " 
Calcium          " 
Aluminium    ** 
Sodium  iodide  

traces. 

105* 
9.3* 

497* 

650* 

0.29* 
132* 
traces. 

0.29* 

158* 
traces. 

traces. 

'  '83 

0.27* 
112* 



traces. 

121* 

90* 

traces. 

25* 
6* 

51* 
10* 

26* 
9* 

"8 

100* 
0.99* 
0.27* 
4 

83* 

83 

15 

2465 

2639 

8 

1368 
8 

34 





17 
96 

513 
60 

17 

"71 

traces, 
traces. 

18 

287 
107 

283 
154 

52 
6 

10 
33 
105 

35 
16 

607 
1343 

"16 

traces. 

traces. 

1041 
22 

38 

0.5 

traces. 

traces. 

traces. 

traces, 
traces. 

Potassium  " 
Sodium  bromide.  .  . 
Potassium     " 
Alumina  



.... 

4 

4 

10 
49 

0.11 

Silex  

44 
traces. 

60 
93 

66 
75 

14 
13 

83 
59 
1173 

27 
75 

2 

Organic  matter.  ... 
Ferrous  sulphate.  .  . 



.... 

Ferrous  crenate.  .  .  . 

1 

A 

1 

I 

H 

! 

1 

Ilardin. 

11 

;  A.  A.  Hayes 

I 

*  Calculated  as  carbonates  instead  of  bicarbonates. 

(51.)  Sodium  sulphide.  78;  ferrous  and  magnesium  sulphides,  traces;  calcium  silicate, 
22.  (52.)  Sodium  sulphide,  41  ;  oxides  of  iron  and  aluminium,  10.  (53.)  Sodium  sulphide, 
19.5.  (55.)  Hydrogen  sulphide,  26.8  c.c.  ;  aluminium  sulphate,  54.8.  (56.)  Magnesium 
bromide,  12  ;  sodium  hyposulphite,  72 ;  sodium  sulphide,  24 ;  silica  and  organic  matter, 
192;  hydrogen  sulphide,  22.37  c.c.  (57.)  Copper  carbonate,  lead  and  barium  sulphates, 
and  arsenic,  traces ;  ammonium  chloride,  0.3;  strontium  sulphate,  29;  sodium  hyposul- 
phite, 0.5;  ammonium  nitrate,  0.94;  carbon  dioxide,  53.7  c.c.  ;  hydrogen  sulphide.  10.6 
c.c.  (58.)  Zmc  pulphate,  333;  ferric  sulphate,  2880  ;  aluminium  sulphate,  1382;  sulphu- 
ric acid  (free),  97.36  ;  phosphoric  acid  and  ammonia,  traces.  (59.)  Hydrogen  sulphide, 
70.6  c.c.  (60.)  Hydrogen  sulphide,  1.7  c.c.  ;  a  peculiar  sulphur  compound,  144. 


HYDROGEN    DIOXIDE.  67 

Physiological. — Water  is  taken  into  the  economy  both  in  its  own 
form  and  as  a  constituent  of  every  article  of  food.  Under  usual  con- 
ditions, the  amount  taken  by  a  healthy  adult  in  twenty-four  hours  is 
2.25  to  2.75  litres,  of  which  1.75  to  2  litres  are  taken  in  the  liquid  form, 
the  remainder  forming  a  part  of  the  solid  food. 

The  amount  of  water  required  by  the  system  is  greater  when  the 
amount  eliminated  by  the  skin  and  kidneys  is  increased,  as  during  ex- 
posure to  high  temperature  and  in  diabetes.  When  the  food  is  dry  the 
amount  of  water  drank  is  increased. 

It  constitutes  about  sixty  per  cent,  of  the  weight  of  the  body;  in  all 
of  whose  tissues  and  fluids  it  exists — most  abundantly  in  the  perspiration 
and  saliva  (99.5$),  and  least  abundantly  in  the  enamel  of  the  teeth  (0.2$). 
The  proportion  of  water  to  solids  in  the  body  is  greater  in  the  earlier 
years  of  life: 

A  fetal  mouse  contained  880  grams  water  in  1,000  grams. 

A  newly  born  mouse  contained        872  grams  water  in  1,000  grams. 

A  mouse  eight  days  old  contained  768  grams  water  in  1,000  grams. 

A  mouse  full-grown  contained         713  grams  water  in  1,000  grams. 

The  consistency  of  the  various  parts  does  not  depend  entirely  upon 
the  relative  proportion  of  solids  and  water,  but  is  influenced  by  the  nature 
of  the  solids.  The  blood,  although  liquid  in  the  ordinary  sense  of  the 
term,  contains  a  less  proportional  amount  of  water  than  does  the  tissue 
of  the  kidneys,  and  about  the  same  proportion  as  the  tissue  of  the  heart. 
Although  the  bile  and  mucus  are  not  as  fluid  as  the  blood,  they  contain 
a  larger  proportion  of  water  to  solids  than  does  that  liquid. 

Water  is  discharged  by  the  kidneys,  intestine,  skin,  and  pulmonary 
surfaces.  The  quantity  discharged  is  greater  than  that  ingested;  the 
excess  being  formed  in  the  body  by  the  oxidation  of  the  hydrogen  of  its 
organic  constituents. 

Hydrogen  Dioxide. 

Peroxide  of  Hydrogen —  Oxygenated  "Water — H2O2 

Discovered  by  Thenard  in  1818.  It  may  be  obtained  in  the  pure  state 
by  accurately  following  a  tedious  process  devised  by  Thenard.  In  a  highly 
diluted  form  it  is  prepared  by  suspending  pure  hydrate  of  barium  dioxide 
in  water,  through  which  a  rapid  current  of  carbon  dioxide  is  then  passed — 

Ba03H2  +  C02=C03Ba+H202, 

the  insoluble  barium  carbonate  being  separated  by  filtration. 

Hydrogen  dioxide  is  also  formed  in  small  quantities  in  the  slow  oxida- 
tion of  metals,  such  as  lead,  zinc,  cadmium,  nickel,  cobalt,  and  aluminium 
in  damp  air,  as  well  as  by  the  slow  oxidation  of  phosphorus,  and  of 
many  organic  substances,  essences,  alcohol,  ether,  etc.,  and  in  the  com- 
bustion of  coal-gas. 

The  pure  substance  is  a  colorless,  syrupy  liquid,  which,  when  poured 
into  water,  sinks  under  it  before  mixing.  It  has  a  disagreeable,  metallic 
taste,  somewhat  resembling  that  of  tartar  emetic.  When  taken  into  the 
mouth  it  produces  a  tingling  sensation,  increases  the  flow  of  saliva,  and 
bleaches  the  tissues  with  which  it  comes  in  contact.  It  has  a  specific 
gravity  of  1.455,  and  is  still  liquid  at  —  30°.  It  is  very  unstable,  and, 
even  in  darkness  and  at  ordinary  temperatures,  is  gradually  decomposed. 


68  GENERAL    MEDICAL    CHEMISTRY. 

At  20°  the  decomposition  takes  place  more  quickly,  and  at  100°  rapidly 
and  with  effervescence.  The  dilute  substance,  however,  is  comparatively 
stable,  and  may  be  boiled  and  even  distilled  without  suffering  decom- 
position. 

This  substance  is  subject'  to  singular  decompositions,  acting  both  as 
a  reducing  and  as  an  oxidizing  agent. 

It  is  rapidly  decomposed,  with  evolution  of  oxygen,  by  contact  with 
gold  or  platinum  in  a  state  of  minute  subdivision,  powdered  charcoal, 
manganese  dioxide,  or  fibrin — the  decomposing  agent  remaining  unaltered. 

Many  elements  and  compounds,  e.  g.,  arsenic,  sulphides,  sulphur 
dioxide,  are  oxidized  when  brought  in  contact  with  hydrogen  peroxide,  at 
the  expense  of  half  its  oxygen. 

If  hydrogen  peroxide  be  brought  in  contact  with  silver  oxide,  both  are 
violently  decomposed,  with  evolution  of  oxygen  and  liberation  of  heat 
and  sometimes  of  light.  Water  and  metallic  silver  remain. 

The  pure  peroxide,  when  decomposed,  yields  475  times  its  volume  of 
oxygen;  the  dilute  substance  15  to  20  times  its  volume. 

The  presence  of  peroxide  of  hydrogen  in  very  minute  quantities  may 
be  detected  by  the  following  tests: 

First. — To  a  solution  of  starch  a  few  drops  of  potassium  iodide  solu- 
tion are  added,  then  a  small  quantity  of  the  fluid  to  be  tested,  and 
finally  a  drop  of  a  solution  of  ferrous  sulphate;  if  hydrogen  peroxide  be 
present,  a  blue  color  is  observed.  This  reaction  may  be  obtained  with  a 
solution  containing  only  0.05  milligram  per  litre  (Schoenbein). 

Second. — A  mixture  of  tincture  of  guaiacum  and  extract  of  malt 
strikes  a  blue  color  in  the  presence  of  oxygenated  water.  Slightly  less 
delicate  than  the  last  (Schoenbein). 

Other  reactions  have  been  proposed  by  Schoenbein,  Barreswill,  Struve, 
and  Weltzien,  which  are,  however,  not  characteristic.  A  colorimetrical 
method  for  determining  the  quantity  of  hydrogen  peroxide  has  been  pro- 
posed by  Schone. 

Dilute  oxygenated  water  is  used  for  renovating  old  pictures  the 
whites  of  which  have  become  dingy  by  the  formation  of  lead  sulphide, 
which  in  the  renovation  is  oxidized  to  the  white  sulphate. 

The  various  bleaching  agents  used  to  convert  brunettes  into  blondes 
are  dilute  solutions  of  oxygenated  water. 


HYDROGEN    FLUOUIDE. 


69 


CLASS  H. 

ELEMENTS  ALL  OP  WHOSE  HYDRATES  ARE  ACIDS,  AND  WHICH  DO  NOT 
FORM  SALTS  WITH  THE  OXACIDS. 

I.     CHLORINE   GROUP. 


FLUORINE  ............  F 

CHLORINE  ............  Cl 

BROMINE  .............  Br 

IODINE  ...............  I 


19 
35.5 

80 


The  elements  of  this  group  are  univalent.  "With  hydrogen  they  form 
acid  compounds,  composed  of  one  volume  of  the  element  in  the  gaseous 
state  with  one  volume  of  hydrogen.  Their  hydrates  are  monobasic  acids 
when  they  exist  (fluorine  forms  no  hydrate).  The  first  two  are  gases, 
the  third  liquid,  the  fourth  solid  at  ordinary  temperatures.  Their  atomic 
weights  increase  from  the  lowest  to  the  highest  by  nearly  16  or  16x3. 
The  relations  of  their  compounds  to  each  other  are  shown  in  the  follow- 
ing table: 

HF, 

Hydroflu-  -  -  —  —  -  --  -  -- 

oric  acid. 


HC1,  C120, 

Hydrochlor-        Chlorine 
ic  acid.          monoxide. 


HBr, 

Hydrobro- 
mic  acid. 


C1203, 
Chlorine 
trioxide. 


C1204, 
Chlorine 
tetroxide. 


HI, 

Hydriodic 
acid. 


I204, 

Iodine 

tetroxide. 


C10H, 
Hypochlor- 
ous  acid. 

BrOH, 

Hypobrom- 
ous  acid. 

IOH, 

Hypoiodous 
acid. 


C10aH, 

Chlorous 

acid. 


IO,H, 
lodous 
acid. 


C103H, 

Chloric 

acid. 

Br03H, 
Bromic 
acid. 

I03H, 
lodic 
acid. 


C104H, 

Perchloric 

acid. 

Br04H, 

Perbrornic 

acid. 

I04H, 

Periodic 

acid. 


FLUORINE. 
ForFl 19 

Although  many  attempts  have  been  made  to  isolate  this  element,  it 
has  probably  never  been  obtained  in  the  free  state,  unless  the  colorless 
gas  obtained  by  G.  J.  and  Th.  Knox,  by  the  decomposition  of  mercury 
fluoride  and  of  hydrofluoric  acid  in  vessels  of  fluor-spar  was  the  element. 
The  difficulty  in  the  way  of  its  separation  lies  in  the  readiness  with  which 
it  attacks  the  metals,  as  well  as  glass,  porcelain,  caoutchouc,  etc.  The 
source  from  which  the  compounds  of  fluorine  are  obtained  is  the  natural 
calcium  fluoride,  or  fluor-spar. 


Hydrogen  Fluoride. 

Hydrofluoric  Acid. 


HF1 


,20 


First  used  for  etching  on  glass,  by  Schwankhard,  in  1670.     Scheele,  in 
1771,  discovered  the  true  nature  of  fluor-spar,  and  gave  this  acid  the  name 


70  GENERAL    MEDICAL    CHEMISTRY. 

of  fluoric  acid.     Hydrofluoric  acid  is  obtained  by  the  action  of  an  excess 
of  sulphuric  acid  upon  fluor-spar,  with  the  aid  of  gentle  heat: 

CaFla  +  S04H2  =  S04Ca  +  2HF1. 

If  a  solution  be  desired,'  the  operation  is  conducted  in  a  platinum  or 
lead  retort,  whose  beak  is  connected  with  a  V-shaped  receiver  of  the 
same  metal,  which  is  cooled  and  contains  a  small  quantity  of  water. 

The  aqueous  acid  is  a  colorless  liquid,  highly  acid  and  corrosive,  and 
having  a  penetrating  odor.  In  using  it  great  care  must  be  exercised  that 
neither  the  solution  nor  the  gas  come  in  contact  with  the  skin,  as  they 
produce  painful  ulcers  which  heal  with  difficulty,  and  also  constitutional 
symptoms  which  may  last  for  days.  When  the  acid  has  accidentally 
come  in  contact  with  the  skin  the  part  should  be  washed  with  dilute  solu- 
tion of  potash,  and  the  vesicle  which  forms  should  be  opened. 

Its  boiling-point  is  between  15°  and  30°.  It  is  still  liquid  at  —40°, 
and  has  a  specific  gravity  of  1.06. 

The  most  interesting  chemical  property  of  hydrofluoric  acid  is  its  ac- 
tion upon  glass,  from  which  it  removes  silica,  a  reaction  which  is  utilized 
in  the  process  of  etching.  For  this  purpose  either  the  vapor  or  the  solu- 
tion may  be  used.  In  either  case  the  glass  surface  is  coated  with  a  var- 
nish composed  of  four  parts  of  yellow  wax  and  one  part  of  turpentine, 
which  is  then  removed  from  those  parts  upon  which  it  is  desired  to  act. 
When  the  solution  is  used  a  wall  of  wax  is  built  up,  and  into  the  reservoir 
thus  formed  the  liquid  is  poured;  by  this  method  a  transparent  design  is 
produced.  It  is  more  usual  to  act  upon  the  glass  with  the  vapor,  as  by 
this  means  an  opaque  and  consequently  more  apparent  design  is  obtained. 
Some  powdered  fluor-spar  is  placed  in  a  shallow  leaden  dish  and  moistened 
with  sulphuric  acid;  the  prepared  glass  plate  is  then  placed,  with  the 
waxed  surface  downward,  upon  the  dish,  which  is  warmed  to  a  tempera- 
ture not  sufficiently  elevated  to  melt  the  wax. 

The  presence  of  fluorine  in  a  compound  is  detected  by  reducing  the 
substance  to  powder,  moistening  it  with  sulphuric  acid  in  a  platinum  cru- 
cible, over  which  is  placed  a  slip  of  glass  prepared  as  above;  at  the  end  of 
half  an  hour  the  wax  is  removed  from  the  glass,  which  will  be  found  to 
be  etched  if  the  substance  examined  contained  a  fluoride. 

Fluorine  forms  no  oxygenated  compounds. 

CHLORINE. 
Cl  ....................  35.5 

Although  probably  first  obtained  by  Glauber,  the  discovery  of  this 
element  is  usually  attributed  to  Scheele,  who  discovered  it  in  1774. 

Its  true  nature  was  first  recognized  by  Sir  Humphrey  Davy  in  1810. 
He  gave  it  the  name  it  bears,  derived  from  x^-wpos  —  yellowish  green  —  in 
reference  to  its  color. 

Preparation.  —  Mrst.  —  By  the  process  followed  by  Scheele,  the  action 
of  manganese  dioxide  on  hydrochloric  acid,  aided  by  heat: 


The  reaction  is,  however,  not  as  simple  as  here  indicated.  Manganic 
chloride,  MnCl4,  is  first  formed  and  then  decomposed  into  free  chlorine  and 
manganous  chloride,  MnCla.  Only  half  the  chlorine  contained  in  the  acid 


CHLOKINE.  71 

is  liberated,  and  each  kilo  of  manganese  dioxide  yields  257.5  litres  of 
chlorine. 

Second. — By  the  action  of  manganese  dioxide  upon  hydrochloric  acid 
in  the  presence  of  sulphuric  acid: 

MnOa + 2HC1 + S04H2 = S04Mn  4-  2HaO + Cla. 

The  same  quantity  of  chlorine  is  obtained  as  in  first,  with  the  use  of 
one-half  the  quantity  of  hydrochloric  acid. 

Third. — By  double  decomposition  of  sodium  chloride  and  sulphuric 
acid,  in  the  presence  of  manganese  dioxide.  A  mixture  of  one  part  each 
of  the  two  solids,  finely  powdered,  is  heated  with  three  parts  of  sulphuric 
acid.  In  this  process  hydrochloric  acid  is  first  formed,  according  to  the 
equation — 

S04Ha + 2NaCl = SO4Naa  +  2HC1.  • 

The  acid,  as  soon  as  found,  is  decomposed  by  either  of  the  reactions 
indicated  in  first  and  second,  according  as  sulphuric  acid  is  or  is  not  pres- 
ent in  excess. 

Fourth. — By  the  action  of  potassium  dichromate  upon  hydrochloric 
acid :  % 

Cra  O7K3  +  14HC1 = 2KC1 + CraCl6 + 7H2O + 3Cla. 

In  this  process,  which  is  convenient,  although  not  economical,  2  parts 
of  powdered  dichromate  are  heated  with  11  parts  of  acid  of  sp.  gr.  1.16; 
the  generating  flask  being  immersed  in  the  water-bath.  100  grams  of 
dichromate  yield  22J  litres  of  chlorine. 

Fifth. — When  a  slow  evolution  of  chlorine,  extending  over  a  con- 
siderable period  of  time,  is  desired,  as  for  purposes  of  disinfection,  moist- 
ened chloride  of  lime  (see  p.  412)  is  exposed  to  the  air.  The  calcium 
hypochlorite  is  decomposed  by  the  atmospheric  carbon  dioxide,  with 
liberation  of  chlorine.  If  a  more  rapid  evolution  of  gas  be  desired,  the 
chloride  of  lime  is  moistened  with  a  dilute  acid  in  place  of  with  water. 

Chlorine  is,  at  the  ordinary  temperature  and  pressure,  a  greenish  yel- 
low gas,  has  a  penetrating  odor,  and  is  very  irritating  to  the  air-passages, 
even  when  highly  diluted  with  air.  Its  specific  gravity  is  2.45  A.  or 
35.5  H.  A  litre  of  chlorine  at  the  normal  temperature  and  pressure 
weighs  3.17  grams.  It  is  quite  soluble  in  water,  one  volume  of  which 
dissolves  three  volumes  of  chlorine  at  10°  0.  It  must  therefor  be  col- 
lected by  displacement  of  air,  the  disengagement-tube  passing  to  the 
bottom  of  the  collecting  vessel,  whose  mouth  is  directed  upward. 

A  saturated  solution  of  chlorine  in  water  is  used  in  the  laboratory, 
where  it  is  known  as  chlorine  water  j  and  medicinally  under  the  names 
Aqua  chlorinii  (U.  $.),  Liquor  chlori  (Br.}.  Good  chlorine  water  bleaches, 
and  does  not  redden  blue  litmus. 

At  a  pressure  of  6  atmospheres  at  0°,  or  at  8J  atmospheres  at  12°, 
chlorine  assumes  the  form  of  an  oily,  yellow  liquid,  whose  density  is  1.33, 
and  whose  boiling-point  is  33.6°.  It  has  not  yet  been  solidified. 

Chlorine  unites  directly  with  all  elements  except  fluorine,  oxygen, 
nitrogen,  and  carbon,  and  with  these,  fluorine  possibly  excepted,  it  is 
capable  of  combining  indirectly.  In  many  instances  the  direct  union  of 
chlorine  with  another  element  is  attended  by  the  liberation  of  light  as 
well  as  of  heat. 


72  GENERAL    MEDICAL   CHEMISTRY. 

At  a  red  heat  chlorine  decomposes  water  readily,  with  the  formation  of 
hydrochloric  acid  and  the  liberation  of  oxygen  : 

2H.O  +  2C1, =41101  +  0,. 

The  same  reaction  takes -place  more  slowly  at  ordinary  temperatures, 
under  the  influence  of  sunlight,  and  for  this  reason  chlorine  water  must, 
be  kept  in  bottles  of  yellow  glass. 

Chlorine  is  an  active  bleaching  and  disinfecting  agent  in  the  presence 
of  water.  Its  action  in  this  respect  is  that  of  an  indirect  oxydant;  it 
decomposes  water,  liberating  oxygen,  which  then  attacks  the  coloring 
or  odorous  organic  matter. 

In  many  instances  chlorine  acts  directly  upon  organic  matters,  a  por- 
tion uniting  with  an  equivalent  number  of  atoms  of  hydrogen  to  form 
hydrochloric  acid  ;  while  another  portion  takes  the  place  of  the  atoms  of 
hydrogen  thus  displaced.  Thus,  with  inarsh-gas,  hydrochloric  acid  and 
methyl  chloride  are  formed  : 

CH4+C12-=CHC1  +  HC1. 

Chlorine  is  capable  of  forming  a  definite  hydrate,  having  the  com- 
position C1.5H2O,  which  is  a  yellowish  green,  crystalline  substance,  formed 
when  chlorine  is  passed  through  chlorine  water  cooled  to  2° — 3°,  and  is 
again  decomposed  when  the  temperature  reaches  10°. 


COMPOUNDS  OF  CHLORINE. 
Hydrogen  Chloride. 

Hydrochloric  acid — Muriatic  acid — Acidum  muriaticum  ( IT.  S.) — 
Acidium  hydrochloricum  (l?r.). — HC1. — Although  known  to  the  alchem- 
ists, in  solution,  as  spirits  of  salt,  hydrochloric  acid  exists  in  nature  in 
small  quantities  only;  in  volcanic  gases  and  in  the  gastric  juice  of  the 
mammalia  (p.  75). 

The  source  whence  hydrochloric  acid  is  obtained,  either  as  an  incidental 
product  or  by  a  special  process,  is  sodium  chloride. 

One  of  the  steps  of  Leblanc's  process  for  the  manufacture  of  sodium 
carbonate  is  the  decomposition  of  sodium  chloride  by  sulphuric  acid: 

2NaCl + SO4H2 = SO4Na3 + 2HC1. 

The  acid,  thus  liberated,  being  very  deleterious  to  both  vegetable  and 
animal  life,  is  passed  through  suitably  arranged  towers,  where  it  meets  a 
descending  stream  of  water,  in  which  it  is  dissolved  to  form,  after  con- 
centration, the  muriatic  acid  of  commerce.  As  Leblanc's  process  is  being 
gradually  superseded  by  another  in  which  hydrochloric  acid  is  not  lib- 
erated (see  p.  398),  the  acid  is  now  specially  prepared  by  the  same  re- 
action. 

Hydrochloric  acid  is  formed  in  a  number  of  other  reactions,  none  of 
•which,  however,  has  been  utilized  for  its  industrial  production.  One 
which  is  of  theoretical  interest,  is  by  the  direct  union  of  its  constituents: 
one  volume  of  hydrogen  and  one  of  chlorine  unite,  under  the  influence  of 
sunlight,  to  form  two  volumes  of  hydrochloric  acid  gas. 


HYDROGEN    CIILOKIDE. 


73 


Hydrochloric  acid  is  a  colorless  gas,  having  an  acid  reaction,  an  acid 
taste,  a  sharp,  penetrating  odor,  and  producing  great  irritation  of  any 
tissue  with  which  it  comes  in  contact.  Its  specific  gravity  is  1.264  A  or 
3(5.5  H.  A  litre  weighs,  at  0°  and  760  mm.,  1.6352  grams.  When  sub- 
jected to  a  pressure  of  40  atmospheres  at  4°,  gaseous  hydrochloric  acid 
assumes  the  liquid  form.  In  contact  with  moist  air  it  forms  white  clouds. 
It  does  not  burn  in  air,  nor  does  it  support  combustion.  It  is  very  solu- 
ble in  water;  one  volume  of  water  at  0°  dissolving  480  volumes,  and  at 
the  ordinary  temperature  460  volumes. 

The  muriatic  or  hydrochloric  acids  used  in  the  arts  and  in  pharmacy 
are  solutions  of  the  gas  in  water  of  different  degrees  of  purity  and  con- 
centration. A  pure,  saturated  solution  in  pure  water  is  a  clear,  colorless 
liquid,  has  a  strongly  acid  taste  and  reaction,  a  specific  gravity  of  1.2, 
and  gives  off  white  fumes  when  exposed  to  the  air.  Non-saturated  solu- 
tions have  lower  specific  gravities,  according  to  the  degree  of  concentra- 
tion. 


SPECIFIC   GRAVITIES   OF   SOLUTIONS   OF   HYDROCHLORIC 

ACID   (Ure). 


Specific 
gravity. 

Acid  of  sp. 
gr.  1.2  in 
100  pts. 

HCl  in  100 
pts. 

Specific 
gravity. 

Acid  of  sp. 
gr.l.2in 
100  pts. 

HCl  in  100 
pts. 

Specific 
gravity. 

Acid  of  sp. 
gr.l.Sin 

100  pts. 

HCl  in  100 
pts. 

1.2000 

100 

40.777 

1.1349 

67 

27.321 

1.0657 

33 

13.094 

1.  1  982 

99 

40.369 

1.1328 

66 

26.913 

1.0637 

32 

12.597 

.1964 

98 

39.961 

1.1308 

65 

26.508 

1.0617 

31 

12.300 

.1946 

97 

39.554 

1.1287 

64 

26.098 

1.0597 

30 

11.903 

.1928 

96 

39.146 

1.1267 

63 

25.690 

1.0577 

29 

11.506 

.1910 

95 

38.738 

1.1247 

62 

25.282 

1.0557 

28 

11.109 

.1893 

94 

38.330 

1.1226 

61 

24.874 

1.0537 

27 

10.712 

.1875 

93 

37.923 

1.1206 

60 

24.466 

1.0517 

26 

10.316 

1.1857 

92 

37.516 

1.1185 

59 

24.058 

1.0497 

25 

9.919 

1.1846 

91 

37.108 

1.1164 

58 

23650 

.0477 

24 

9.522 

1.1822 

90 

36.700 

1.1143 

57 

23.242 

.0457 

23 

9.126 

1.1802 

89 

36.292 

1.1123 

56 

22.834 

.0437 

22 

8.729 

1.1782 

88 

35.884 

1.1102 

55 

22.426 

.0417 

21 

8.332 

1.1762 

87 

35.476 

1.1082 

54 

22019 

.0397 

20 

7.935 

1.1741 

86 

35.068 

1.1061 

53 

21.611 

.0377 

19 

7.558 

1.1721 

85 

34.660 

1.1041 

52 

21.203 

1.0357 

18 

7.141 

1.1701 

84 

34.252 

1.1020 

51 

20.796 

1.0337 

17 

6.745 

1.1681 

83 

33.845 

1.1000 

50 

20.388 

1.0318 

16 

6.348 

1.1661 

82 

33.437 

.0980 

49 

19.980 

1.0308 

15 

5.951 

1.1641 

81 

33.029 

.0960 

48 

19.572 

1.0279 

14 

5.554 

1.1620 

80 

32.621 

.0939 

47 

19.165 

1.0259 

13 

5.158 

1.1599 

79 

32.213 

.0919 

46 

18.757 

1.0239 

12 

4.762 

1.1578 

78 

31.805 

.0899 

45 

18.340 

1.0220 

11 

4.365 

1.1557 

77 

31.398 

1.0879 

44 

17.941 

1.0200 

10 

3.998 

1.1536 

76 

30.990 

1.0859 

43 

17.534 

1.0180 

9 

3.571 

1.1515 

75 

30.582 

1.0838 

42 

17.126 

.0160 

8 

3.174 

1.1494 

74 

30.174 

1.0818 

41 

16.718 

.0140 

7 

2.778 

1.1473 

73 

29.767 

1.0798 

40 

16.310 

.0120 

6 

2.381 

1.1452 

72 

29.359  ! 

1.0778 

39 

15.902 

.0110 

5 

1.984 

1.1431 

71 

28.951 

1.0758 

38 

15.494 

.0080 

4 

1.588 

1.1410 

70 

28.544 

1.0738 

37 

15.087 

.0060 

3 

1.191 

1.1389 

69 

28.136 

1.0718 

36 

14.679 

1.0040 

2 

0.795 

1.1369 

68 

27.728 

1.0697 

35 

14.271 

1.0020 

1 

0.397 

1.0677 

34 

13.863 

74  GENERAL    MEDICAL    CHEMISTRY. 

The  boiling-point  of  hydrochloric  acid  solution  varies  with  the  con- 
centration. It  is  the  highest,  111.11°,  with  an  acid  of  sp.  gr.  1.094. 
When  concentrated  hydrochloric  acid  is  boiled,  the  totality  of  the  gas 
is  not  expelled;  when  it  reaches  the  composition  of  the  hydrate  HC1, 
8H2O,  nearly  corresponding  to  the  specific  gravity  given  above,  its  boiling- 
point  remains  stationary  and"  an  acid  ef  the  same  composition  distils 
over. 

The  varieties  of  the  acid  solutions  used  in  the  arts  and  in  medicine 
are  : 

Commercial  muriatic  acid,  a  yellow  liquid;  specific  gravity  about 
1.1G;  contaminated  with  iron,  with  chloride  of  sodium,  and  with  arsenical 
compounds.  It  is  used  only  for  manufacturing  and  coarse  chemical  pro- 
cesses. 

C.  P.  hydrochloric  acid,  a  colorless  liquid,  usually  far  from  pure 
(see  below). 

Acidum  muriaticum  ( IT.  S.} — Acidum  hydrochloricum.  (l?r.),  a 
colorless  liquid,  of  sp.  gr.  1.16  =  32.3$  of  the  gaseous  acid,  which  contains 
small  quantities  of  impurities. 

Acidum  muriaticum  dilutum  ( IT.  /S.) — Acidum  hydrochloricum  dil. 
(Er.).— The  last,  diluted  with  water  to  sp.  gr.  1.038,  U.  S.  (1.052,  Br.),  and 
containing  7.74  per  cent.  HC1.  (10.6  per  cent.,  Br.). 

Hydrochloric  acid  is  ranked,  with  nitric  and  sulphuric  acids,  as  one  of 
the  strong  mineral  acids.  It  is  decomposed  by  many  metals,  with  liber- 
ation of  hydrogen  and  formation  of  a  chloride: 

2HCl+Zn=:ZnCl2  +  H2. 

With  oxides  and  hydrates  it  enters  into  double  decomposition,  form- 
ing water  and  a  chloride: 

CaO  +  2HCl=CaCl1  +  H1O. 
CaH302  +  2HC1= CaCla  +  2H2O. 

Most  of  the  metallic  chlorides  are  readily  soluble  in  water,  mercurous, 
silver,  and  lead  chlorides  being  exceptions. 

By  the  action  of  oxidizing  agents,  hydrochloric  acid  is  decomposed 
•with  liberation  of  chlorine,  as  in  the  reaction  between  it  and  potassium 
dichromate  (p.  71).  The  chlorine,  being  thus  in  the  nascent  state,  is 
capable  of  uniting  with  gold  or  platinum  to  form  chlorides  of  those  me- 
tals. The  same  liberation  of  chlorine  takes  place  in  the  mixture  of  nitric 
and  hydrochloric  acids,  in  the  proportion  of  one  molecule  of  the  former 
to  three  of  the  latter,  known  as  Aqua  regia,  Acid,  nitro-muriaticum 
(U.  S.),  Acid,  nitro-hydrochloricum  (JBr.). 

Compounds  formed  by  the  substitution  of  a  metal  or  radical  for  the 
hydrogen  of  hydrochloric  acid  are  called  chlorides. 

Analytical. — The  presence  of  hydrochloric  acid,  or  of  a  chloride  in 
solution,  may  be  detected  by  the  formation  of  a  white,  Hocculent  pre- 
cipitate with  silver  nitrate,  which  is  soluble  in  ammonia,  but  insoluble 
in  nitric  acid  (see  p.  81). 

Impurities. — Hydrochloric  acid  should  be  perfectly  colorless.  It 
should  give  no  coloration  with  potassium  sulphocyanate  (iron).  When 
shaken  with  chloroform,  the  latter  should  not  be  colored  (bromine  and 
iodine).  It  should  not  precipitate  with  solution  of  barium  chloride,  in 


HYDROGEN    CHLORIDE.  75 

solution  of  sulphur  dioxide  (chlorine).  It  should  give  no  reaction  when 
tested  for  arsenic  by  Otto's  method.* 

Physiological. — The  existence  of  free  hydrochloric  acid  in  the  gastric 
juice  was  first  noted  by  Prout  in  1824,  and  proved  by  Schmidt  in  1852. 
Although  Lehmann,  Blondlot,  Bernard  and  others  have  thought  other- 
wise, subsequent  investigations  have  fully  confirmed  the  results  of 
Schmidt. 

Toxicology. — Notwithstanding  the  frequent  use  of  this  acid  in  the 
arts,  it  is  very  rarely  administered  with  murderous  intent,  owing  to  its 
pronounced  odor  and  taste.  Several  cases  are  recorded,  however,  in 
which  it  has  been  taken  either  by  accident,  or  with  suicidal  intent.  Its 
action  is  similar  to  that  of  sulphuric  acid  (q.  v.),  but  not  as  intense,  ex- 
cept in  so  far  as  the  larynx  is  concerned.  The  treatment  consists  in  neu- 
tralizing the  acid  as  quickly  as  possible  by  the  administration  of  an  alkali, 
or  of  magnesia. 

The  detection  of  the  acid  in  the  body  after  death  requires  a  quanti- 
tative determination.  Stains  produced  by  the  acid  upon  colored  cloth 
are  of  a  brighter  red  than  those  produced  by  sulphuric  acid,  and  do  not 
destroy  the  fibre  of  the  cloth  to  so  great  an  extent.  They  disappear 
when  moistened  with  aqua  ammoniae,  if  they  be  not  too  old. 

Distinction  between  ^>oisons  and  corrosives. — Although  the  delete- 
rious action  exerted  by  certain  substances  when  they  are  taken  into 
the  stomach  in  small  quantities  has  been  known  and  made  use  of  by  the 
evilly  inclined  from  the  earliest  antiquity,  the  definition  of  a  poison  has 
been  difficult.  The  element  of  quantity,  although  it  is  an  important 
factor  in  the  method  of  action  of  deleterious  substances,  does  not  afford 
ground  upon  which  to  base  the  desired  definition,  as  it  is  impossible  to 
fix  definitely  the  dose  of  any  poison  which  is  necessarily  lethal.  Almost 
all  substances,  if  taken  in  sufficient  quantity,  produce  derangements 
which  may  terminate  in  death. 

There  is  this  distinction  between  the  methods  of  action  of  true  poisons 
and  of  corrosives,  such  as  the  mineral  acids  :  the  former  do  not  reveal 
their  lethal  character  until  they  have  been  absorbed  into  the  circulation  • 
the  latter  act,  not  through  the  blood,  but  by  coming  into  immediate  con- 
tact with  and  destroying  some  organ  essential  to  life.  Sulphuric  acid 
will  destroy  life  as  surely  by  disintegrating  a  large  surface  of  skin  as  it 
will  by  corroding  the  coats  of  the  stomach.  Both  actions  are  due  to  the 
same  quality  of  the  acid,  yet,  if  we  include  sulphuric  acid  among  the 
poisons,  we  are  forced  to  the  unphilosophical  conclusion  of  considering  it 
a  poison  when  it  destroys  the  stomach,  but  not  when  it  corrodes  another 
equally  essential  organ. 

The  best  definition  of  a  poison  we  believe  to  be  the  following  :  Any 
.substance  which,  after  absorption  into  the  blood,  produces  death  or  serious 
bodily  harm.  The  question  of  quantity  is  thus  avoided,  and,  according 
to  our  definition,  as  in  accordance  with  fact,  the  same  substance  is  or  is 
not  a  poison,  as  it  is  taken  in  quantities  sufficient  or  insufficient  to  pro- 
duce harmful  results. 

The  mineral  acids  and  alkalies,  acting  at  their  points  of  immediate 
•contact  with  the  tissues,  find  a  place  medically  and  toxicologically  under 
the  head  of  corrosives,  and  legally  among  the  "  other  noxious  or  destruc- 
tive things  "  mentioned  in  statutes  relating  to  poisoning. 

*  Ausmittel  d.  Gifte,  5th  ed.,  p.  97,  note. 


76  GENERAL    MEDICAL    CHEMISTRY. 


Compounds  of  Chlorine  and  Oxygen. 

Three  compounds  of  chlorine  and  oxygen  have  been  isolated,  two 
being  anhydrides.  They  are  all  very  unstable,  and  prone  to  sudden  and 
violent  decomposition. 

Chlorine  monoxide,  C\.iO=hypochlorous  anhydride  or  oxide,  is  ob- 
tained by  the  action  of  dry  chlorine  upon  cooled,  precipitated  mercuric 
oxide — 

HgO+2Cl2=HgCl2  +  Cl20, 

as  a  blood-red,  mobile  liquid  below  20°.  Above  that  temperature  it  is  a 
reddish  yellow  gas,  having  a  penetrating  odor  similar  to  that  of  chlorine. 
It  is  decomposed  with  an  explosion  upon  the  slightest  jar,  and  even 
spontaneously.  When  brought  into  contact  with  water  it  slowly  forms  a 
nearly  colorless  solution,  containing  hypochlorous  acid,  C1OH,  which  may 
be  more  readily  obtained  in  solution  by  passing  a  current  of  chlorine 
through  water  holding  recently  precipitated  calcium  carbonate  in  sus- 
pension, and  subjecting  the  solution  to  distillation,  the  receiver  being 
well  cooled. 

This  solution  is  a  yellow  liquid,  having  an  acrid  taste  and  an  odor  of 
chlorine.  It  is  an  exceedingly  active  oxidizing  and  bleaching  agent. 
Owing  to  its  instability,  the  acid  itself  is  not  used  industrially,  although 
its  salts,  the  hypochlorites  of  calcium,  potassium  and  sodium  are  (see 
pp.  412,  401,  398). 

Chlorine  trioxide,  C12O3= chlorous  anhydride  or  oxide,  is  obtained 
by  the  action  of  dilute  nitric  acid  upon  potassium  chlorate,  in  the  pres- 
ence of  arsenic  trioxide.  It  is  a  greenish  yellow  gas  ;  decomposes  at 
about  50°  C.,  with  explosion;  soluble  in  water;  has  strong  bleaching 
powers,  and  an  irritating  action  upon  the  air-passages  when  inhaled.  Its 
aqueous  solution  contains  chlorous  acid,  ClOaH — a  very  unstable  body, 
which  has  not  been  isolated,  corresponding  to  a  series  of  salts  called 
chlorites. 

Chlorine  tetroxide,  C12O4= chlorine  peroxide,  a  violently  explosive 
body,  obtained  by  the  action  of  concentrated  sulphuric  acid  upon  potas- 
sium chlorate.  Below  — 20°  it  is  an  orange-red  liquid,  and  above  that 
temperature  a  yellow  gas,  probably  composed  of  ClaO-hCl  O.  Although 
this  body  is  sometimes  improperly  called  hypochloric  acid,  there  is  no 
corresponding  hydrate;  and  if  it  be  brought  in  contact  with  an  alkaline 
hydrate,  a  mixture  of  the  chlorate  and  chlorite  of  the  metal  is  formed: 

Cla04 + 2KHO = C103K + C102K + H3O. 

Besides  the  above,  there  exist  two  other  oxacids  of  chlorine,  whose  cor- 
responding anhydrides  have  not  been  isolated.  These  are  chloric  and 
perchloric  acids. 

Chloric  acid,  C1O3H — obtained  in  aqueous  solution,  by  decomposing 
its  barium  salt  with  the  proper  quantity  of  dilute  sulphuric  acid.  As 
thus  obtained,  it  is  a  syrupy  liquid,  colorless  or  yellowish,  and  strongly 
acid.  It  decomposes  at  40°,  and  is  an  energetic  oxydant. 

Perchloric  acid,  C1O4H — the  most  stable  of  the  series,  is  prepared  by 
boiling  potassium  chlorate  with  hydrofluosilicic  acid,  cooling,  decanting 
the  clear  fluid,  which  is  evaporated  and  from  time  to  time  decanted  until 


HYDKOGEN    BROMIDE.  77 

white  fumes  appear,  when  it  is  distilled.  It  is  a  colorless,  oily  liquid, 
sp.  gr.  1.782;  explodes  on  contact  with  organic  substances  or  charcoal; 
corrodes  animal  tissues  energetically. 

It  enters  into  the  composition  of  chlorodyne. 


BROMINE. 
Br 80 

Discovered  by  Balard  in  1826.  Its  name  is  derived  from  j3po5juof,  an 
evil  odor.  It  does  not  exist  free  in  nature,  but  is  found  in  combination 
with  the  alkaline  metals  and  magnesium,  widely  diffused,  but  in  small 
quantities. 

It  is  obtained  from  the  mother-liquors  of  salt  springs,  especially  those 
of  Stassfurth  and  Kreuznach  in  Germany,  and  of  Pomeroy,  Ohio;  from 
the  mother-liquor  left  in  the  manufacture  of  sea-salt;  and  from  kelp  (see 
p.  78).  These  are  subjected  to  distillation  with  manganese  dioxide  and 
sulphuric  acid,  by  which  the  bromides  are  decomposed  and  elementary  bro- 
mine liberated. 

At  ordinary  temperatures,  bromine  is  a  dark,  reddish  brown  liquid; 
has  a  strong,  disagreeable  odor,  somewhat  resembling  that  of  chlorine  ; 
is  irritating  to  the  air-passages,  and  corrodes  animal  tissues  with  which 
it  comes  in  contact. 

It  is  volatile  at  all  temperatures  above  its  point  of  solidification, 
giving  off  red  fumes.  It  boils  at  63°.  Its  freezing-point  is  variously 
given  from  —  7.3°  to  —  24.5°.  The  latter  is  probably  the  correct  one,  the 
higher  freezing-points  of  some  samples  being  due  to  the  presence  of 
water.  Sp.  gr.  3.1872  at  0°.  Soluble  in  water  to  the  extent  of  3.2  parts 
in  100  at  15°.  When  the  solution  is  cooled  to  0°  in  the,  presence  of  an 
excess  of  bromine,  a  crystalline  hydrate,  Br.5H2O,  is  formed.  It  is  more 
soluble  in  alcohol,  carbon  disulphide,  chloroform,  and  ether,  than  in  water. 
Its  solutions,  which  are  yellow  or  brown,  according  to  concentration,  are 
decomposed  by  exposure  to  light,  with  formation  of  hydrobromic  acid. 

Its  chemical  properties  are  the  same  as  those  of  chlorine  in  kind,  but 
less  energetic. 

It  is  highly  poisonous,  but,  owing  to  its  comparative  rarity  and  its 
powerful  odor,  only  one  case  of  death  from  its  action  has  been  recorded. 

Free  bromine  may  be  recognized  by  its  odor,  by  the  yellow  or  brown 
color  of  its  chloroform  solution,  and  by  the  yellow  or  orange  color  which 
it  communicates  to  starch  paste.  (For  the  analytical  reactions  of  the 
bromides,  see  p.  81.) 

Hydrogen  Bromide. 

Hydrobromic  acid,  HBr. — This  acid  cannot  be  obtained  by  decom- 
position of  a  bromide  as  hydrochloric  acid  is  obtained  by  decomposition 
of  a  chloride,  as  it  is  destroyed  by  the  presence  of  any  excess  of  sulphuric 
acid.  It  is  obtained  by  the  action  of  water  upon  phosphorus  tribromide — 

PBr3  +  3H.O =P03H3  +  3HBr, 

or  by  the  action  of  bromine  upon  paraffine. 

It  is  a  colorless  gas;  produces  white  clouds  on  contact  with  air;  li- 
quefies at  —69°,  and  solidifies  at  — 73°;  has  an  acid  taste  and  reaction,  and 


78  GENERAL    MEDICAL    CHEMISTRY. 

dissolves  readily  in  water,  with  which  it  forms  a  definite  hydrate,  HBr 
2H2O.  Its  chemical  properties  are  similar  to  those  of  the  corresponding 
chlorine  compound.  Its  hydrogen  is  replaceable  by  metals  to  form 
bromides. 

Oxacids  of  Bromine. 

No  oxides  of  bromine  are  known,  although  three  oxacids  exist,  either 
in  the  free  state  or  as  salts: 

Hypobromous  acid — BrOH — may  be  obtained,  in  aqueous  solution, 
by  the  action  of  bromine  upon  mercuric  oxide,  silver  oxide,  or  silver  ni- 
trate. When  bromine  is  added  to  concentrated  solution  of  potassium 
hydrate,  no  hypobromite  is  found,  but  a  mixture  of  bromate  and  bromide, 
having  no  decolorizing  action.  With  sodium  hydrate,  however,  sodium 
hypobromite  is  formed  in  solution,  and  such  a  solution,  freshly  prepared, 
is  used  in  Knop's  process  for  determining  urea  (p.  264). 

JSromic  acid — BrO3H — is  readily  obtained,  in  aqueous  solution,  by 
the  action  of  chlorine  upon  bromine,  in  the  presence  of  water,  or  by  the 
decomposition  of  barium  bromate,  suspended  in  water,  by  sulphuric  acid. 
In  combination  as  a  bromate,  it  is  obtained  by  the  action  of  bromine 
upon  a  solution  of  potassium  hydrate — 

6KHO  +  3Bra = BrO3K  +  5KBr  +  3H2O, 

the  bromate  being  separated  from  the  bromide  by  taking  advantage  of  its 
more  sparing  solubility. 

Perbromic  acid — BrO4H — is  obtained  as  a  comparatively  stable,  oily 
liquid,  by  the  decomposition  of  perchloric  acid  by  bromine,  and  concen- 
trating over  the  water-bath.  It  is  noticeable  in  this  connection  that, 
while  hydrochloric  acid  and  the  chlorides  are  more  stable  than  the  corre- 
sponding bromine  compounds,  the  oxygen  compounds  of  bromine  are  more 
permanent  than  those  of  chlorine. 


IODINE. 

..127 


Discovered  in  1811  by  Courtois;  further  studied  by  Gay-Lussac  in 
1814,  and  by  Sir  H.  Davy  at  about  the  same  time.  Name  derived  from 
1008179,  violet,  referring  to  the  color  of  its  vapor. 

Iodine  has  not  been  found  to  exist  in  nature  in  the  free  state,  but  in 
combination  it  is  widely  disseminated  in  the  three  kingdoms  of  nature, 
without,  however,  being  anywhere  abundant.  The  iodides  of  potassium, 
sodium,  calcium,  and  magnesium  exist  in  small  quantities  in  sea-water,  in 
the  waters  of  mineral  springs,  and  indeed,  in  mere  traces,  in  most  natural 
waters;  more  abundantly  in  the  ashes  of  marine  plants,  sponges,  molluscs 
and  polyps,  as  well  as  in  the  bodies  of  animals  living  in  salt  water.  Cod- 
liver  oil  contains  appreciable  quantities  of  iodine — according  to  De  Jongh, 
37  parts  in  100,000. 

Iodine  is  obtained  almost  exclusively  from  the  ashes  of  sea-weeds 
collected  in  Scotland  and  in  the  north  of  France.  The  weeds  are  burned, 
and  the  ash,  known  as  kelp  in  Scotland,  and  as  varech  in  France,  is  ex- 
tracted with  water,  and  the  solution  subjected  to  fractional  crystalliza- 


IODINE.  79 

tion.  The  last  concentrated  mother-liquid,  which  refuses  to  crystallize, 
contains  the  iodides;  they  are  decomposed  by  a  current  of  chlorine,  aided 
by  heat;  the  iodine  being  thus  driven  off,  is  collected  in  suitable  con- 
densing-chambers. 

It  occurs  in  iron-gray,  brittle,  crystalline  scales,  having  a  metallic 
lustre,  and  a  sp.  gr.  of  4.948  at  17°.  It  melts  at  113.6°  and  boils  at  175°. 
Its  vapor  is.  of  a  rich  violet  color.  It  volatilizes  at  all  temperatures,  the 
vapor  condensing  in  the  crystalline  form.  The  density  of  the  vapor  is 
8.716  A,  or  127  H.  It  has  a  peculiar  and  characteristic  odor,  and  a  disa- 
greeable taste;  is  sparingly  soluble  in  water,  which  takes  up  a  larger 
quantity,  however,  on  standing  over  an  excess  of  iodine — owing  to  the 
formation  of  hydriodic  acid,  in  a  solution  of  which  iodine  is  more  soluble 
than  in  pure  water.  The  solubility  of  iodine  is  very  much  increased  by 
the  presence  of  certain  salts,  notably  of  potassium  iodide.  A  solution  of 
iodine  in  solution  of  potassium  iodide  is  used  in  medicine,  under  the 
names  Liq.  iodinil  compositus  (II.  /£),  Liq.  iodl  (JBr.),  LugoVs  solution. 
Iodine  is  soluble  in  alcohol  (Tlnct.  iodinil),  and  in  ether  with  a  brown 
color;  in  chloroform,  benzol,  and  carbon  disulphide,  with  a  violet  color. 

Its  chemical  properties  are  similar  to  those  of  chlorine  and  bromine, 
but  less  marked.  In  the  presence  of  water,  iodine  exerts  a  slight  oxidiz- 
ing and  decolorizing  action.  It  decomposes  hydrogen  sulphide  with  lib- 
eration of  elementary  sulphur  and  formation  of  hydrogen  iodide.  It  does 
not  combine  with  ordinary  oxygen,  but  does  with  ozone.  It  unites  directly 
with  many  of  the  metalloids,  and  with  most  of  the  metals,  to  form  iodides. 
It  dissolves  in  solution  of  potassium  hydrate,  with  formation  of  potassium 
iodide  and  some  hypoiodide.  Nitric  acid  oxidizes  it  to  iodic  acid.  With 
ammonium  hydrate  it  forms  nitrogen  iodide  (q.  v.). 

Free  iodine  may  be  detected  by  the  blue-violet  color  which  it  com- 
municates to  starch,  and  by  the  violet  color  of  its  solutions  in  carbon 
disulphide  and  chloroform. 

Commercial  iodine  is  liable  to  contamination  with  foreign  substances. 
Of  these,  non-volatile  bodies,  such  as  manganese  dioxide,  graphite,  etc., 
may  be  detected  and  separated  by  subliming  the  iodine.  Water  has  been 
found  to  be  used  as  an  adulterant  of  iodine  in  as  large  quantity  as  twenty 
per  cent.;  it  renders  the  iodine  moist  and  sticky;  and  when  iodine  so 
adulterated  is  dissolved  in  carbon  disulphide,  the  water  separates  in  a  dis- 
tinct layer.  Chlorides  of  calcium  and  magnesium  have  also  been  detected 
in  iodine.  The  most  serious  contamination,  however,  is  that  with  the 
iodide  of  cyanogen,  which  is  probably  formed  during  the  process  of  manu- 
facture, by  the  decomposition  of  cyanides  contained  in  the  kelp.  The 
scales  of  iodine  so  contaminated  have  upon  their  surfaces  minute,  white, 
acicular  crystals.  To  detect  and  at  the  same  time  separate  this  impurity 
when  present  even  in  very  small  quantities,  heat  one  ounce  of  the  iodine 
over  the  water-bath  in  a  porcelain  dish,  covered  by  a  flat-bottomed  flask 
containing  cold  water.  After  about  twenty  minutes'  heating  the  iodide 
of  cyanogen  will  have  collected  on  the  bottom  of  the  flask,  in  white  acicu- 
lar crystals. 

Action  on  the  Economy. 

When  brought  in  contact  with  the  skin  it  produces  irritation  and  a 
brown  stain,  which,  however,  soon  disappears.  When  taken  internally, 
it  acts  both  as  a  local  irritant  to  the  surfaces  of  the  intestinal  canal,  with 
which  it  cornes  in  contact,  and  as  a  true  poison.  Cases  of  acute  iodine 


80  GENERAL    MEDICAL    CHEMISTRY. 

poisoning  are  not  common,  and  those  recorded  are  due  to  accident  or  neg- 
ligence, with  one  exception,  in  which  homicide  was  prevented  by  the 
color  communicated  to  the  starchy  fluid  with  which  the  iodine  was  mixed. 
It  is  probable  that  when  iodine  is  administered  internally,  it  is  converted 
into  hydriodic  acid  (q.  v.)  during  the  processes  of  assimilation.  At  all 
events,  it  is  ultimately  discharged  as  argalkaline  iodide  by  the  urine  and 
saliva,  but  not  by  the  perspiration,  whether  it  be  taken  as  free  iodine  or 
as  potassium  iodide;  when  taken  in  large  quantities,  it  also  appears  in 
the  fseces.  The  treatment  consists  in  removing  the  poison  by  emetics  or 
the  stomach-pump,  as  rapidly  as  possible. 


Hydrogen  Iodide. 

Hydriodic  acid  —  HI.  —  Hydriodic  acid  does  not  exist  in  nature.  For 
its  preparation  recourse  is  had  to  the  decomposition  of  phosphorus  tri- 
iodide  by  water: 

PI,  +  3H20  =  P03H3  +  SHI. 

Red  phosphorus  is  placed  in  a  retort,  under  water  ;  the  proper  quantity 
of  iodine  is  then  added  and  the  retort  heated. 

When  desired  in  solution,  it  is  more  readily  obtained  by  directing  a 
current  of  hydrogen  sulphide  through  water  holding  iodine  in  suspension  — 


and  filtering  from  the  precipitated  sulphur.  This  is  the  method  directed 
by  the  U.  S.  P. 

Hydrogen  iodide  is  a  colorless  gas,  fuming  on  contact  with  air,  having 
a  strong  acid  reaction  and  a  penetrating  odor.  Sp.  gr.  4.443  A  —  64.2  H. 
By  cold  and  pressure  it  may  be  condensed  to  a  yellow  liquid,  which  solidi- 
fies at  —  55°.  It  is  very  soluble  in  water,  one  volume  of  which,  at  10°, 
dissolves  425  volumes  of  the  gas.  The  saturated  solution  has  a  density 
of  1.7.  When  heated,  like  hydrochloric  acid  solution,  it  gives  off  a  part 
of  its  gas,  until  the  boiling-point  becomes  stationary  at  126°,  when  the 
remainder  distils  without  decomposition. 

Hydriodic  acid  is  decomposed  into  its  component  elements  when 
heated  —  the  decomposition  being  only  partial,  as  the  same  influence 
brings  about  a  partial  union  of  the  elements.  When  a  mixture  of  hydriodic 
acid  and  oxygen  is  ignited,  iodine  is  set  free  and  water  is  formed.  The 
same  action  takes  place  when  the  mixture  is  exposed  to  sunlight. 
Aqueous  solutions  of  hydriodic  acid,  when  exposed  to  the  light,  quickly 
become  brown  from  a  decomposition  of  the  acid,  with  separation  of  ele- 
mentary iodine.  Hydriodic  acid  is  also  decomposed  by  a  number  of  other 
substances  ;  by  many  metals  with  formation  of  metallic  iodides  and 
liberation  of  hydrogen;  by  chlorine  and  bromine  with  liberation  of  iodine; 
by  sulphuric  and  nitric  acids,  also  with  liberation  of  iodine;  and  by  many 
chlorides,  with  formation  of  hydrochloric  acid  and  an  iodide: 

PC1,+3HI=PI1  +  3HC1. 

The  readiness  with  which  it  gives  up  its  hydrogen  renders  it  a  valuable 
source  of  that  element  in  the  nascent  state,  for  which  purpose  it  is  used 
in  organic  chemistry. 


OXACIDS    OF    IODINE.  81 

In  aqueous  solution  it  is  officinal  in  the  U.  S.  P.  as  Acid,  hydriodicum 
.j  which,  however,  is  very  prone  to  decomposition.        , 


Analytical  Characters. 

Chlorides,  bromides,  and  iodides. — The  detection  and  determination 
of  any  one  of  these  classes  of  compounds  is  simple  in  the  absence  of  the 
other  two.  When  it  is  uncertain,  as  is  usually  the  case,  whether  there 
be  not  two  or  more  of  them  present,  the  determination  becomes  more 
difficult.  Silver  nitrate  forms  a  precipitate  with  either  of  the  three, 
which  is  white,  or  yellowish  if  the  bromide  or  iodide  be  present  in  large 
quantity,  and  is  insoluble  in  dilute  nitric  acid.  Ammonium  hydrate  dis- 
solves the  precipitate  very  readily  in  the  case  of  the  chloride,  much  less 
readily  in  that  of  the  bromide,  and  with  great  difficulty  in  that  of  the 
iodide. 

The  best  means  of  distinguishing  between  the  three  is  by  adding  a 
few  drops  of  carbon  disulphide  and  chlorine  water;  upon  shaking  the 
mixture  the  disulphide  is  colored  violet  in  the  presence  of  an  iodide, 
yellow  or  orange  by  bromine,  and  remains  colorless  if  neither  bromide 
nor  iodide  be  present. 

Cyanides  also  give  a  white  precipitate  with  silver  nitrate,  insoluble  in 
dilute  nitric  acid  and  rather  soluble  in  ammonium  hydrate  ;  they  are 
detected  by  the  characters  given  on  p.  340. 

For  the  methods  of  detecting  small  quantities  of  these  salts  in  the 
presence  of  each  other,  and  for  their  estimation,  see  the  works  of  Rose, 
Fresenius,  and  Gerhard  and  Chancel. 


Oxacids  of  Iodine. 

The  best  known  of  these  are  the  highest  two  of  the  series — iodic  and 
periodic  acids. 

Jodie  acid — IO3H — does  not  exist  in  nature.  It  is  formed  as  an 
iodate,  whenever  iodine  is  dissolved  in  a  solution  of  an  alkaline  hydrate — 


I6 + 6KHO = I03K  +  5KI + 3HaO, 

as  the  free  acid,  by  the  action  of  strong  oxidizing  agents,  such  as  nitric 
acid  or  chloric  acid,  upon  iodine;  or  by  passing  chlorine  for  some  time 
through  water  holding  iodine  in  suspension.  The  preparation  and  puri- 
fication of  iodic  acid  are  always  tedious. 

Iodic  acid  appears  in  white  crystals,  decomposable  at  170°,  and  quite 
soluble  in  water,  the  solution  having  an  acid  reaction,  and  a  bitter,  as* 
tringent  taste. 

It  is  an  energetic  oxidizing  agent,  yielding  up  its  oxygen  readily,  with 
separation  of  elementary  iodine  or  of  hydriodio  acid.  It  is  used  as  a  test 
for  the  presence  of  morphine  (q.  v.). 

Periodic  acid  •  IO4H — is  formed  by  the  action  of  chlorine  upon  an 
alkaline  solution  of  sodium  iodate.  The  sodium  salt  thus  obtained  is  dis- 
solved in  nitric  acid,  treated  with  silver  nitrate,  and  the  resulting  silver 
periodate  decomposed  with  water.  From  the  solution  the  acid  is  ob- 
tained in  colorless  crystals,  fusible  at  130°,  very  soluble  in  water,  and 
readily  decomposable  by  heat. 
6 


82 


GENERAL    MEDICAL    CHEMISTRY. 


II.  SULPHUR  GROUP. 


SULPHUR S  . 

SELENIUM Se 

TELLURIUM  .  . .  Te 


32 

,  79.5 
128 


The  elements  of  this  group  are  divalent.  With  hydrogen  they  form 
compounds  composed  of  one  volume  of  the  element,  in  the  form  of  vapor, 
with  two  volumes  of  hydrogen — the  combination  being  attended  with  a 
condensation  in  volume  of  one-third.  Their  hydrates  are  dibasic  acids. 
They  are  all  solid  at  ordinary  temperatures.  The  relation  of  their  com- 
pounds to  each  other  are  shown  in  the  following  table : 


H2S, 

Hydrogen 
sulphide. 

H2Se, 

Hydrogen 

selenide. 

H2Te, 
Hydrogen 
telluride. 


S02, 
Sulphur 
dioxide. 

Se02, 
Selenium 
dioxide. 

Te( 
Tellui 
dioxide. 


S03, 
Sulphur 
trioxide. 

Se03, 
Selenium 
trioxide. 

Te03, 
Tellurium 
trioxide. 


S02H2, 

Hyposulphu- 

rous  acid. 


S03Ha, 

Sulphurous 

acid. 

Se03H2, 

Selenious 

acid. 

Te03H2, 

Tellurous 
acid. 


S04H2, 

Sulphuric 

acid. 

Se04H2, 

Selenic 

acid. 

Te04H2, 

Telluric 

acid. 


SULPHUR. 


32 


This  element  has  been  known  in  its  own  form  from  remote  antiquity. 
It  was  called  Otlov  by  the  Greeks.  It  occurs  in  actively  volcanic  regions, 
in  crystalline  powder,  in  large  crystals,  or  amorphous.  It  is  brought 
principally  from  Sicily,  Iceland,  and  the  vicinity  of  Naples,  where  it  is 
found  near  "  solfatarse,"  which  are  vents  in  the  craters  of  extinct  volcanoes, 
through  which  gases  still  issue. 

The  native  sulphur  is  always  accompanied  by  more  or  less  earthy 
matter,  from  which  it  is  separated  by  two  distillations:  one  in  the  locality 
where  it  is  collected,  the  product  of  which  is  crude  sulphur  ;  and  a 
second,  in  a  more  perfect  apparatus,  which  yields  refined  sulphur.  This 
is  in  one  of  two  forms.  During  the  first  portion  of  the  distillation,  while 
the  air  of  the  condensing-chamber  is  still  cool,  the  vapor  of  sulphur  is 
condensed  in  the  form  of  a  fine  powder,  known  as  flowers  of  sulphur,  and 
composed  of  minute  crystals.  At  a  later  stage,  when  the  temperature 
of  the  condensing-chamber  reaches  114°,  the  sulphur  collects  at  the  bot- 
tom as  a  liquid  ;  this  is  drawn  off  from  time  to  time,  and  cast  into  elon- 
gated, conical  moulds,  forming  roll  sulphur.  Its  physical  properties  are 
affected  by  various  conditions.  Generally,  sulphur  appears  as  a  light  yel- 
low solid,  having  neither  taste  nor  odor.  At  low  temperatures  (below 
— 50°),  and  when  in  a  state  of  fine  subdivision,  it  is  almost  colorless. 

It  is  dimorphous;  crystallizes  in  oblique  rhombic  prisms  when  fused 
sulphur  is  allowed  to  solidify,  and  in  rhombic  octohedra  when  its  solution 


COMPOUNDS    OF    HYDROGEN    AND    SULPHUR.  83 

in  carbon  disulphide  is  allowed  to  evaporate  spontaneously.  The  two 
forms  differ  from  each  other  in  specific  gravity  :  that  of  the  prismatic 
sulphur  being  1.95,  and  that  of  the  octohedral  2.05.  The  fusing-point 
of  the  first  variety  is  120°;  that  of  the  second  114.5°.  The  prismatic 
variety  does  not  remain  such  indefinitely  ;  transparent  at  first,  it  gradu- 
ally becomes  opaque  from  a  conversion  of  the  prisms  into  collections  of 
octohedra. 

When  sulphur  is  heated  it  melts  to  a  thin,  yellow  liquid  at  about  114°; 
at  from  150°  to  160°  this  becomes  thick  and  brown  ;  toward  330°  to  340° 
it  becomes  thinner  and  lighter  in  color  again,  and,  finally,  it  boils  at  a 
temperature  variously  stated  from  440°  (Deville)  to  448°  (Becquerel), 
giving  off  a  brownish  yellow  vapor.  When  heated  to  about  400°  and 
suddenly  cooled,  it  is  converted  into  still  another  variety,  known  as 
2^lastic  sulphur,  which,  for  a  time,  is  reddish  brown,  transparent,  elastic, 
and  so  soft  that  it  may  be  moulded  into  any  desired  form.  At  1,000° 
the  density  of  vapor  of  sulphur  is  2.22A  or  31.75H.  The  best  solvents 
of  sulphur  are  protochloride  of  sulphur  and  carbon  disulphide,  a  solution 
in  the  former  containing  66.7  per  cent,  of  sulphur  at  ordinary  tempera- 
tures, and  the  latter  dissolving  37.2  parts  per  100  at  15°.  It  is  also 
soluble  to  a  less  extent  in  aniline,  phenol,  benzol,  benzine,  and  chloroform. 

Sulphur  may  be  obtained  as  a  white,  very  finely  divided  powder,  by 
the  decomposition  of  calcium  sulphide.  As  thus  prepared,  it  is  the  Sul- 
phur prcecipitatum  (U.  S.,  Br.),  or  milk  of  sulphur. 

Sulphur  unites  readily  with  other  elements,  forming  compounds 
which,  except  those  formed  with  elements  of  the  chlorine  group  and 
oxygen,  are  known  as  sulphides.  When  heated  in  contact  with  air  or 
oxygen,  it  burns  with  a  blue  flame,  giving  off  sulphur  dioxide,  SO2.  In 
an  atmosphere  of  hydrogen  it  burns  with  formation  of  hydrogen  sulphide. 

The  compounds  of  sulphur  resemble  in  composition,  and  to  some  ex- 
tent in  their  chemical  properties,  the  corresponding  oxygen  compounds 
when  these  exist.  Thus,  carbon  disulphide,  CS2,  is  an  anhydride  corre- 
sponding to  carbon  dioxide,  CO2.  In  many  organic  substances  sulphur 
may  be  made  to  replace  oxygen;  thus,  we  have  sulphocyanic  acid,  CNSH, 
corresponding  to  cyanic  acid,  CNOH.  Sulphur  is  used  in  the  arts,  prin- 
cipally for  the  manufacture  of  gunpowder;  also  to  some  extent  in  making 
sulphuric  acid,  sulphur  dioxide,  and  matches,  and  for  the  prevention  of 
parasitic  growths.  It  is  not  used  medicinally  to  the  same  extent  as 
formerly.  We  have  only  theoretical  explanations  of  the  method  in 
which  it  is  rendered  capable  of  absorption.  That  it  is  absorbed  when 
taken  internally  is,  however,  certain,  from  the  fact  that  persons  taking  it 
excrete  by  the  skin  sufficient  quantities  of  some  compound  of  sulphur  to 
blacken  silver  coins  carried  in  their  clothing. 


Compounds  of  Hydrogen  and  Sulphur. 

Two  of  these  are  known — similar  in  composition  to  the  oxygen  com- 
pounds: 

Hydrogen  sulphide H2S. 

Hydrogen  persulphide H2S2. 

It  is  probable  that   there  also  exist   other  compounds  containing  a  still 
higher  proportion  of  sulphur. 


84  GENERAL    MEDICAL    CHEMISTRY. 


Hydrogen  Sulphide. 

Sulphydric  acid—Hydrosidphuric  acid  —  Sulphuretted  hydrogen  —  • 
H2S  —  exists  in  nature  in  the  volcanic  gases;  as  a  result  of  the  decompo- 
sition of  organic  matters  containing  sulphur;  and  in  solution  in  the  wa- 
ters of  some  mineral  springs. 

It  may  be  obtained  by  the  direct  union  of  the  elements,  either  by 
burning  sulphur  in  hydrogen,  or  by  passing  a  current  of  hydrogen 
through  molten  sulphur.  At  high  temperatures  vapor  of  sulphur  decom- 
poses water  with  formation  of  hydrogen  sulphide  and  pentathionic  acid. 
It  is  also  formed  by  the  action  of  nascent  hydrogen  upon  sulphuric  acid,  in 
the  presence  of  zinc,  if  the  mixture  become  heated.  This  last  method  of 
formation  is  of  interest  in  connection  with  Marsh's  test  for  arsenic  (q.  v.). 

When  desired  in  the  laboratory,  it  is  obtained  by  one  of  the  three  fol- 
lowing reactions: 

First.  —  By  the  action  of  hydrochloric  acid  upon  antimony  trisulphide: 

Sb2S3  +  6HC1  =  2SbCl3  +  3H2S. 

Second.  —  The  process  usually  adopted  is  by  the  action  of  diluted  sul- 
phuric acid  upon  ferrous  sulphide: 

FeS  +  SO4H2  =  SO4Fe  +  H2S. 

Third.  —  When  the  gas  is  required  for  toxicological  analysis,  it  is  es- 
sential that  it  should  contain  no  hydrogen  arsenide  (which  has  been 
shown  by  Myers  to  be  capable  of  existence  in  the  presence  of  hydrogen 
sulphide);  and  as  it  is  difficult  to  obtain  ferrous  sulphide  free  from 
arsenic,  which  would  be  converted  into  hydrogen  arsenide  under  the  con- 
ditions required  for  the  formation  of  hydrogen  sulphide,  Otto  has 
recommended  that  hydrogen  sulphide  be  obtained  in  such  cases  by  the 
action  of  hydrochloric  acid  upon  calcium  sulphide  (q.  v.): 

CaS+2HCl:=CaCl2  +  H2S. 

By  whatever  method  hydrogen  sulphide  is  prepared,  it  must  be  washed 
before  use  by  bubbling  through  water. 

Hydrogen  sulphide  is  a  colorless  gas,  having  the  odor  of  rotten  eggs, 
and  a  correspondingly  disgusting  taste;  sp.  gr.  1.19  A  —  17.2  H.  Water 
at  15°  dissolves  3.23  times  its  volume  of  the  gas,  which  is  also  soluble  in 
alcohol.  At  —  74°,  at  the  ordinary  pressure,  or  under  a  pressure  of  17 
atmospheres,  it  liquefies;  and  solidfies  at  —85.5°,  into  white  crystals.  The 
density  of  the  liquid  is  0.9. 

Hydrogen  sulphide  burns  in  air  with  formation  of  sulphur  dioxide  and 
water: 


If  the  supply  of  oxygen  be  deficient,  water  is  formed  and  elementary 
sulphur  deposited: 


Mixtures  of  hydrogen  sulphide  and  oxygen,  or  air,  explode  on  the  ap- 
proach of  a  flame.     When  hydrogen   sulphide  in  solution  is  exposed  to 


ACTION    ON    THE    ECONOMY.  85 

the  air,  it  is  decomposed  into  separation  of  sulphur.  Solutions  should  be 
made  with  boiled  water  and  kept  in  bottles,  which  are  completely  filled 
and  well  corked.  Oxidizing  agents  decompose  hydrogen  sulphide  readily 
with  separation  of  sulphur;  it  is  also  similarly  decomposed  by  chlorine, 
bromine  and  iodine,  which  unite  with  its  hydrogen.  Sulphur  dioxide  and 
hydrogen  sulphide  mutually  decompose  each  other  (see  p.  87). 

When  the  gas  is  passed  through  a  solution  of  an  alkaline  hydrate,  the 
oxygen  of  the  hydrate  is  displaced  by  sulphur,  with  formation  of  a  sulphy- 
drate: 

HaS  +  KHO=H, 


When  directed  through  a  solution  of  a  metallic  salt,  hydrogen  sul- 
phide relinquishes  its  sulphur  to  the  metal  — 

SO4Cu  +  H2S  =  CuS  +  SO4H2 

—  a  property  which  renders  it  of  great  value  in  analytical  chemistry. 

The  presence  of  hydrogen  sulphide,  even  in  minute  quantities,  may 
be  detected  by  its  odor,  and  by  the  brown  or  black  coloration  which  it 
produces  in  a  piece  of  filter-paper  moistened  with  solution  of  lead  acetate. 


Action  on  the  Economy. 

Hydrogen  sulphide  exists  in  small  quantity  in  the  gases  of  the  intes- 
tine, where  it  results  from  the  decomposition  of  albuminous  material,  or 
from  that  of  taurocholic  acid;  it  also  occurs  occasionally  in  abscesses  and 
in  the  urine  in  tuberculosis,  variola,  and  cancer  of  the  bladder,  resulting 
from  the  decomposition  of  some  unknown  sulphurized  body.  In  certain 
•exceptional  cases  the  gas  may  also  reach  the  bladder  by  diffusion  from 
tiie  rectum  (Betz). 

When  inhaled,  hydrogen  sulphide  is  an  active  poison.  An  animal 
placed  in  an  atmosphere  of  the  gas  dies  almost  immediately,  and  the 
moderately  diluted  gas  is  still  rapidly  fatal.  The  minimum  proportion  in 
which  it  is  fatal  to  human  life  is  stated  by  Letheby  to  be  one  per  cent., 
although  Gaultier  de  Claubry  claims  that  workmen  have  existed  for  some 
time  in  an  atmosphere  containing  three  per  cent.  Even  when  highly 
diluted,  it  produces,  when  inhaled,  a  low,  febrile  condition;  and  care 
should  be  had  that  the  air  of  laboratories  in  which  it  is  used  is  not  con- 
taminated by  it. 

The  researches  of  Kaufmann  and  Rosenthal,  Diakonaw  and  Preyer, 
leave  no  doubt  that  the  toxic  effects  of  hydrogen  sulphide  are  due  prima- 
rily, if  not  entirely,  to  its  reducing  and  combining  with  the  coloring- 
matter  of  the  red  blood-corpuscles. 

Sewer-gases. — It  is  but  rarely  that  a  human  being  inhales  simple  mix- 
tures of  air  with  hydrogen  sulphide.  The  latter  generally  produces  its 
deleterious  effects  as  a  constituent  of  the  gases  emanating  from  sewers, 
privies,  burial-vaults,  etc.,  in  which  it  exists  both  in  its  own  form  and  as 
ammonium  sulphydrate.  Cases  of  accidental  (if  the  adjective  be  admis- 
sible) poisoning  from  sewer-gases  are  of  two  forms:  1.  Slow  poisoning, 
sometimes  terminating  fatally,  by  sewer-gases  diluted  with  air  and  trace- 
able to  defective  plumbing;  generally  in  dwellings  "  fitted  with  all  the 
modern  conveniences."  Very  common,  although  easily  preventable  by 


86  GENERAL    MEDICAL    CHEMISTRY. 

proper  trapping  and  ventilation  of  soil-  and  waste-pipes.  2.  Cases  which 
may  be  designated  as  acute,  in  which  the  gas  is  inhaled  in  a  more  concen- 
trated form,  as  by  those  entering  sewers  or  engaged  in  the  removal  of 
night-soil.  The  victim  usually  falls  as  if  by  the  effect  of  a  sudden  blow,, 
and,  even  if  rescued  within  a  few  moments,  frequently  dies  within  twenty- 
four  hours. 

The  treatment  should  consist  in  promoting  the  inhalation  of  fresh  air — 
by  artificial  respiration  if  necessary,  cold  affusions,  the  administration 
of  hot  brandy  and  water,  and  the  inhalation  of  air  containing  a  trace  of 
chlorine. 

In  cases  of  death  the  blood  is  very  dark  in  color,  and  on  spectroscopic 
examination  shows  the  bands  of  sulphgemoglobin. 


Sulphur   Dioxide. 

Sulphurous  anhydride — Sulphurous  acid — Sulphurous  oxide — SO2. — 
Sulphur  dioxide  exists  in  volcanic  gases,  and  in  solution  in  some  natural 
waters. 

It  is  prepared  by  burning  sulphur  in  air.  This  method  is  adopted 
when  the  gas  is  required  as  a  disinfectant,  and  in  some  sulphuric  acid 
factories. 

By  roasting  iron  pyrites  in  a  current  of  air,  in  most  sulphuric  acid 
factories. 

During  the  combustion  of  coal  or  coke  containing  sulphur,  and  of 
coal-gas  contaminated  with  carbon  disulphide. 

By  heating  strong  sulphuric  acid  with  copper  turnings: 

2SO4H2 + Cu = SO4Cu  +  2HaO  +  SO2. 

The  acid  is  brought  in  contact  with  the  metal  and  heated  until  the 
action  begins,  after  which  the  heat  is  moderated,  or,  if  the  action  become 
too  violent,  withdrawn  entirely.  This  is  the  method  followed  for  obtain- 
ing the  gas  in  the  laboratory.  The  product  must  be  passed  through  a 
small  quantity  of  water.  The  same  reduction  of  sulphuric  acid  is  accom- 
plished by  other  substances,  such  as  sulphur,  carbon,  mercury,  and  silver. 
According  to  the  United  States  and  British  Pharmacopoeias,  charcoal  is 
to  be  used. 

Sulphur  dioxide  is  a  colorless  gas,  having  a  suffocating  odor  (that  of 
burning  sulphur  matches),  and  a  disagreeable  and  persistent  taste.  Sp- 
gr.  2.234  A — 32.25  H.  It  may  be  easily  liquefied  at  — 10°,  forming  a 
colorless,  mobile,  transparent  liquid,  which  solidifies  at  — 75°  and  boils  at 
—  8°.  By  a  rapid  evaporation  of  the  liquid,  a  temperature  of  —65°  is- 
obtained.  It  is  very  soluble  in  water,  which,  at  15°,  dissolves  more  than 
forty  times  its  volume.  It  is  also  very  soluble  in  alcohol. 

Sulphur  dioxide  is  not  a  supporter  of  combustion,  nor  will  it  burn  in 
air.  "When  heated  in  contact  with  hydrogen,  it  is  decomposed  with 
formation  of  water  and  separation  of  sulphur.  In  presence  of  nascent 
hydrogen,  however,  hydrogen  sulphide  and  water  are  formed. 

Water  not  only  dissolves  the  gas;  but  forms  with  it  a  true  hydrate, 
SO3H2,  which  exists  in  the  solution.  A  hydrate  of  this  acid,  crystalline,, 
fusible  at  +  4°,  and  having  the  composition  SO3H2-}-8H2O,  has  been  sepa- 
rated. While,  therefor,  the  name  sulphurous  acid  is  incorrect  as  applied 
to  the  gas,  it  is  perfectly  applicable  to  the  solution.  Such  a  solution  is- 


SULPHUR   TRIOXIDE.  87 

officinal  under  the  name  Acidum  sulphurosum  (U.  S.,  Br.)  (U.  S.  sp.  gr., 
1.035  —  Br.  sp.  gr.  1.04;  both  nearly  saturated  at  the  ordinary  tempera- 
ture). 

It  is  a  valuable  reducing  agent,  for  which  purpose  it  is  frequently 
used,  either  in  the  gaseous  form  or  in  solution.  Its  deoxidizing  power  is 
due  to  the  absorption  of  oxygen  by  the  sulphurous  acid  to  form  sulphuric 
acid: 


It  decolorizes  vegetable  substances,  without,  however,  permanently 
destroying  the  pigment;  for  if  an  organic  substance,  bleached  by  sulphur 
dioxide,  be  washed  with  dilute  sulphuric  acid,  the  color  is  restored.  Its 
bleaching  power  is  utilized  in  the  manufacture  of  straw,  silk,  and  woollen 
goods.  It  is  probable  that  this  decoloration  is  due  to  an  oxidation  of 
sulphurous  acid  at  the  expense  of  the  oxygen  of  water,  the  nascent  hy- 
drogen uniting  with  the  coloring-matter  to  form  a  colorless  compound, 
as  indigotine  is  converted  into  white  indigo  by  the  action  of  reducing 
agents.  It  is  also  used  as  a  disinfecting  and  deodorizing  agent  —  probably 
behaving  toward  other  organic  matters  as  toward  the  pigments.  Its  chief 
value,  however,  for  this  purpose  is  in  the  destruction  of  hydrogen  sul- 
phide, which  it  brings  about  with  formation  of  water  and  pentathionic 
acid,  and  liberation  of  sulphur: 


In  this  case  it  is  not  a  reducing,  but  an  oxidizing  agent. 

Sulphur  dioxide  and  chlorine  combine  directly  under  the  influence  of 
sunlight  to  form  a  liquid  having  the  composition  SO2C12,  the  chloride  of 
the  divalent  radical  sulphuryl  (SO2)",  which  also  exists  in  sulphuric  acid, 
and  which  may  be  considered  as  existing  free  in  sulphur  dioxide,  as 
carbonyl  (CO)''  exists  free  as  carbonic  oxide. 

Corresponding  to  sulphurous  acid,  which  is  dibasic,  are  salts  known  as 
sulphites. 

Although  poisonous  when  inhaled  in  the  concentrated  form,  it  can  only 
be  regarded  as  annoying  when  largely  diluted  with  air;  moreover,  in- 
dividuals become  quickly  habituated  to  inhaling  air  containing  compara- 
tively large  quantities  of  this  gas.  A  delicate  reagent  for  the  presence 
of  sulphur  dioxide  is  obtained  by  moistening  paper,  impregnated  with 
starch  paste,  with  a  solution  of  iodic  acid;  a  mere  trace  of  the  gas,  1  to 
3,000,  in  air,  is  sufficient  to  reduce  the  iodic  acid,  when  the  liberated  iodine 
produces  a  blue  color  with  the  starch. 


Sulphur  Trioxide. 

Sulphuric  anhydride — Sulphuric  oxide,  SO3. — Although  formed  by 
the  direct  union  of  sulphur  dioxide  and  oxygen,  at  250°-300°,  and'in  the 
presence  of  spongy  platinum,  this  substance  is  more  easily  obtained  from 
Nordhausen  sulphuric  acid  (q.  v.),  by  distillation  at  a  temperature  below 
100°,  and  collection  of  the  vapors  in  a  condenser  cooled  by  a  mixture  of 
ice  and  salt. 

It  appears  in  the  form  of  white,  silky  needles.     It  is  capable  of  exist- 


88  GENERAL    MEDICAL    CHEMISTRY. 

ing  in  two  forms,  which  differ  from  each  other  in  their  fusing  and  boiling 
points.  It  has  a  great  tendency  to  unite  with  water  to  form  sulphuric 
acid — 

S03  +  H20=S04H2, 

and  when  exposed  to  the  ahr  it  gives  c>ff  white  fumes  of  that  substance, 
formed  by  union  with  atmospheric  moisture.  When  it  is  thrown  into 
water  a  hissing  sound  is  observed,  and  there  is  a  marked  elevation  of  tem- 
perature. When  perfectly  pure  it  does  not  redden  dry,  blue  litmus 
paper ;  nor  has  it  any  corrosive  action  upon  animal  tissues  until,  by 
absorption  of  moisture,  it  is  converted  into  sulphuric  acid. 

Berthelot  has  described  another  oxide  of  sulphur,  having  the  composi- 
tion S2O7 — an  unstable,  crystalline  body,  formed  by  the  union  of  sulphur 
dioxide  and  oxygen,  under  the  influence  of  silent  electric  discharges. 

Oxacids  of  Sulphur. 

These  compounds  form  an  extended  series,  some  of  the  terms  of 
which  are  very  important  industrial  products.  They  may  be  divided  into 
two  groups,  some  of  the  members  of  which  are  known  only  in  combi- 
nation. 


SO2H2  Hydrosulphurous  acid. 
SO3H2  Sulphurous  acid. 
SO4H2  Sulphuric  acid. 


S0OJEL  Dithionic  acid. 


83 


S3O6H2  Trithionic  acid. 
S4O6H2  Tetrathionic  acid. 


SBO6H2  Pentathionic  acid. 
S2O3H2  Hyposulphurous  acid. 
S2O7H2  Pyrosulphuric  acid. 

It  is  unfortunate  that  the  name  hyposulphurous  acid  (hyposulphites), 
should  have  been  applied  and  retained  by  usage,  to  the  compound 
S2O3H2,  as  it  properly  belongs  to  SO2H2;  discovered  by  Schtitzenberger 
in  1869.  The  so-called  hyposulphurous  acid  may  be  considered  as  formed 
by  the  union  of  two  molecules  of  SO2H2,  with  separation  of  a  molecule  of 
water;  or  as  sulphuric  acid  in  which  one  atom  of  oxygen  has  been  re- 
placed by  an  atom  of  sulphur. 

Hydrosulphurous  Acid— SO2H2. 

Is  only  known  in  solution,  in  which  form  it  is  obtained  by  the  action 
of  zinc  upon  sulphurous  acid  in  solution.  It  is  an  unstable  body,  and  a 
powerful  bleaching  and  deoxidizing  agent.  Upon  its  deoxidizing  power 
Schtitzenberger  and  Risler  have  based  a  process  for  the  quantitative 
determination  of  oxygen,  admirably  adapted  for  use  in  analysis  of  blood.* 

Sulphuric   Acid— SO4H2. 

This  acid,  or  rather  the  commercial  product  containing  it,  is  manufac- 
tured in  enormous  quantities,  and  may  be  said  to  be  the  basis  of  chemical 
industry,  as  there  are  but  few  processes  of  chemical  technology  into 
some  part  of  which  it  does  not  enter. 


*  Bull.  Soc.  Chim.  Paris,  xix.,  152  ;  xx.,  145. 


SULPHURIC    ACID.  89 

It  was  known  to  the  earlier  alchemists  as  spirits  of  Roman  vitriol; 
they  obtained  it  by  the  distillation  of  ferrous  sulphate,  a  method  still  fol- 
lowed for  the  manufacture  of  the  so-called  Nordhausen  acid  (q.  v.). 

The  method  by  which  the  commercial  acid  is  now  obtained  is  the  re- 
sult of  gradual  improvement,  through  a  period  of  time  beginning  in  the 
early  part  of  the  seventeenth  century.  In  its  present  form  it  may  be  divided 
into  two  parts:  1st,  the  formatio.n  of  a  dilute  acid;  and  2d,  the  concen- 
tration of  this  product. 

The  first  part  is  carried  on  in  immense  chambers  of  timber,  lined  with 
lead,  and  furnishes  an  acid  having  a  specific  gravity  of  1.55,  and  containing 
sixty-five  per  cent,  of  true  sulphuric  acid,  SO4H2.  Into  these  leaden  cham- 
bers sulphur  dioxide,  obtained  by  burning  sulphur  or  by  roasting  pyrites, 
is  driven  along  with  a  large  excess  of  air.  In  the  chambers  it  comes  in, 
contact  with  nitric  acid,  at  the  expense  of  which  it  is  oxidized  to  sul- 
phuric acicf,  while  nitrogen  tetroxide  (red  fumes)  is  formed: 

S02  +  2N03H=S04H2  +  2N02. 

Were  this  the  only  reaction,  not  only  would  the  cost  of  sulphuric  acid 
be  much  greater  than  it  is,  but  the  disposal  of  the  red  fumes  would  offer 
serious  obstacles  to  its  manufacture.  To  avoid  these  difficulties,  a  second 
reaction  is  resorted  to.  Water  in  the  form  of  steam,  or  of  fine  spray,  is 
discharged  into  the  chambers,  and,  coming  in  contact  with  the  nitrogen. 
tetroxide,  converts  part  into  nitric  acid  and  part  into  nitrogen  dioxide  : 

3NO2  +  H20=2N03H  +  NO. 

The  nitrogen  dioxide,  in  contact  with  the  oxygen  of  air  carried  into 
the  chamber,  forms  nitrogen  tetroxide  — 


which  in  turn  yields  more  nitric  acid.  These  series  of  changes  go  on  con- 
tinuously, the  supply  of  sulphur  dioxide  and  water  being  carefully  regu- 
lated to  the  required  proportions,  and  the  nitric  acid  acting  merely  as  a 
-carrier  of  oxygen  from  the  air  to  the  acid. 

The  acid  is  allowed  to  collect  in  the  chambers  until  it  has  the  sp.  gr. 
1.55,  when  it  is  drawn  off.  This  chamber  acid,  although  used  in  a  few 
industrial  processes,  is  not  yet  strong  enough  for  most  purposes.  It  is 
concentrated,  first  by  evaporation  in  shallow  leaden  pans  until  its  specific 
gravity  reaches  1.746;  at  this  point  it  begins  to  act  upon  the  lead,  and 
is  transferred  to  platinum  stills,  where  the  concentration  is  completed. 

The  product  is  of  three  grades,  according  to  the  extent  to  which  the 
concentration  has  been  carried:  sp.  gr.  1.833  =  93  per  cent.,  SO4HQ;  sp.  gr. 
1.840=98  per  cent.,  $O4H2;  and  sp.  gr.  1.840=99|-  per  cent.,  SO4H2. 

The  commercial  acid  is  an  oily  liquid,  having  a  more  or  less  pro- 
nounced brown  tinge,  and  is  known  as  oil  of  vitriol.  It  still  contains 
many  impurities,  from  which  it  is  partially  freed  by  distillation  in  glass, 
the  product  being  the  so-called  C.  P.,  or  chemically  pure  acid,  which  is, 
however,  rarely  so. 

The  pure  acid  is  a  colorless,  oily  liquid;  sp.  gr.  1.842  at  12°;  solidifies 
at  10.5°,  and  boils  at  338°,  although  ebullition  seems  to  begin  at  290°.  It 
is  odorless,  intensely  acid  in  reaction  arid  in  taste,  and  highly  corrosive. 


90 


GENERAL    MEDICAL    CHEMISTRY. 


The  specific  gravity  varies  with  the  amount   of  water,  as  shown   in   the 
following  table: 


DENSITIES  OF  SOLUTIONS  OF   SULPHURIC  ACID   AT    +15°, 

AFTER  J.  KOLB. 


Degree 
Baume. 

<§£ 
11 

in  bo 

«S 

O1-1 

S| 

a 

»S 

ft  03 

«_>, 
11 

02  60 

t/3  u 

1 

«§ 
a* 

8s® 

1 

sc 

02  Ib 

„§ 
o* 

"| 

1 
^ 

n 

0 

1.000 

0.7 

0.9 

23 

1.190 

21.1 

25.8 

46 

1.468 

46.4 

56.9 

1 

1.007 

1.5 

1.9         24 

1.200 

22.1 

27.1 

47 

1.483 

47.6 

58.3 

2 

1.014 

2.3 

2.8         25 

1.210 

23.2 

28.4 

48 

1.498     48.7 

59.6 

3 

1.0.22 

3.1 

3.8 

26 

1.220 

24.2 

29.6 

49 

1.514 

49.8 

61.0 

4 

1.029 

3.9 

4.8 

27 

1.230 

25.3 

31.0 

50 

1.530 

51.0 

62.5 

5 

1.037 

4.7 

5.8 

28 

1.241 

26.3 

32.2 

51 

1.540  !  52.2 

64.0 

6 

1.045 

5.6 

6.8 

29 

1.252 

27.3 

33.4 

52 

1.563 

53.5 

65.5 

7 

1.052 

6.4 

7.8 

30 

1.263 

28.3 

34.7 

53 

1.580 

54.9 

67.0 

8 

1.060 

7.2 

8.8 

31. 

1.274 

29.4 

36.0 

54 

1.597     56.0 

68.6 

9     1.067 

8.0 

98 

32 

1.285 

30.5 

37.4   i 

55 

1.615  L  57.1 

70.0 

10 

1.075 

8.8 

10.8 

33 

1.297 

31.7 

38.8   i 

56 

1.634 

58.4 

71.6 

11 

1.083 

9.7 

11.9 

34 

1.308 

32.8 

40.2   ; 

57 

1.652 

59.7 

73.2 

12 

1.091 

10.6 

13.0 

35 

1.320 

33.9 

41.6 

58 

1.671 

61.0 

74.7 

13 

1.100 

11.5 

14.1 

36 

1.332 

35.1 

43.0 

59 

1.691 

62.4 

76.4 

14 

1.108 

12.4 

15.2 

37 

1.345 

36.2 

44.4 

60 

1.711 

63.7 

78.1 

15 

1.116 

13.2 

16.2   ! 

38 

1.357 

37.2 

45.5 

61 

1.732     65.2   l    79.9 

16 

1.125 

14.1 

17.3 

39 

1.370 

38.3 

46.9 

62 

1.753     66.7 

81.7 

17 

1.134 

15.1 

18.5 

40 

1.383 

39.5 

48.3 

63 

1.774     68.7 

84.1 

18 

1.142 

16.0 

19.6 

41 

1.397 

40.7 

49.8 

64 

1.796     70.6 

86.5 

19 

1.152 

17.0 

20.8 

42 

1.410 

41.8 

51.2 

65 

1.819 

73.2 

89.7 

20 

1.162 

18.0 

22.2 

43 

1.424 

42.9 

52.8 

66 

1.842 

81.6 

100.0 

21 

1.171 

19.0 

23.3 

44 

1.433 

441 

54.0 

22 

1.180 

20.0 

24.5 

45 

1.453 

45.2 

55.4 

1 

When  the  vapor  of  sulphuric  acid  is  heated  to  redness,  it  is  decom- 
posed into  oxygen,  water,  and  sulphur  dioxide.  It  is  also  reduced,  with  for- 
mation of  sulphur  dioxide,  by  many  substances,  such  as  sulphur,  phos- 
phorus, carbon,  mercury,  copper,  and  silver. 

Sulphur  trioxide  unites  with  water  to  form  at  least  three  definite 
hydrates:  one,  the  compound  S2O7H2,  which  will  be  considered  below; 
another,  the  so-called  monohydrated  acid,  SO4H2,  or,  true  sulphuric  acid; 
and  a  third,  sometimes  called  the  bihydrated  acid,  having  the  composition 
SO  H 2  +  H  O,  which  crystallizes  in  large  prisms,  fusible  at  +8.5°:  sp.  ST. 
1.788. 

When  sulphuric  acid  is  mixed  with  water,  there  is  an  elevation  of 
temperature  which  amounts  to  100°  when  four  volumes  of  acid  are  mixed 
with  one  volume  of  water.  The  tendency  of  sulphuric  acid  to  absorb  water  is 
such  that  it  is  frequently  used  as  a  drying  agent,  absorbing  water  from  the 
surrounding  air  or  from  gases  which  are  caused  to  bubble  through  it. 
For  the  same  reason  it  is  unsafe  to  leave  the  acid  in  a  vessel  exposed  to 
the  air,  as  it  is  liable  to  absorb  moisture  to  such  an  extent  that  by  in; 
crease  of  bulk  it  overflows.  When  mixtures  of  acid  arid  water  are  to  be 
made,  the  acid  should  be  added  to  the  water  (in  a  vessel  of  thin  glass). 

Owing  to  its  affinity  for  water,  sulphuric  acid  destroys  many  organic 


ACTION    ON    THE    ECONOMY.  91 

substances,  removing  from  them  the  elements  of  water,  and,  in  the  case 
of  the  carbohydrates,  leaving,  a  residue  of  carbon. 

Sulphuric  acid  is  a  powerful  dibasic  acid. 

The  presence  of  sulphuric  acid  or  of  a  soluble  sulphate  may  be  de- 
tected by  the  formation  of  a  white  precipitate  of  barium  sulphate  with 
chloride  or  nitrate  of  barium  in  an  acid  solution.  This  precipitate,  when 
dried,  mixed  with  charcoal  and  strongly  heated,  is  converted  into  barium 
sulphide;  which,  when  moistened  with  hydrochloric  acid,  gives  off  hydro- 
gen sulphide,  recognizable  by  the  blackening  of  paper  moistened  with 
solution  of  lead  acetate. 

There  are  three  varieties  of  sulphuric  acid  used  in  pharmacy.  The 
Ac'tdum  sulphur  icum  (U.  S.,  Br.),  the  so-called  C.  P.  acid,  having  a 
specific  gravity  of  1.842,  used  only  in  the  preparation  of  other  pharma- 
ceutical preparations;  Acidum  sulphuricum  dilutum  (U.  S.,  Br.),  the  last 
mentioned  diluted  with  water  to  sp.  gr.  1.082  U.  S.,  containing  11.9^ 
SO4H2  (sp.  gr.  1.094,  Br.,  containing  about  13$  SO4H2);  Ac.  sulph.  aro- 
maticum  (U.  S.,  Br.),  containing  about  the  same  proportion  of  acid  as 
the  Ac.  sulph.  dil.,  U.  S. 

Impurities. — The  commercial  acid  is  so  charged  with  foreign  sub- 
stances as  to  render  it  entirely  unfit  for  medicinal  and  for  any  but  the 
coarsest  chemical  uses.  Even  the  C.  P.  acid  is  obtained  sufficiently  free 
from  certain  impurities  for  toxicological  analysis  only  with  considerable 
difficulty.  The  principal  impurities  are  the  following:  lead,  recognizable 
by  the  production  of  cloudiness  when  the  acid  is  diluted  with  water, 
lead  sulphate  being  less  soluble  in  dilute  than  in  concentrated  acid. 
Potassium  sulphate,  fraudulently  added  to  increase  the  specific  gravity, 
may  be  detected  by  evaporating  to  dryness.  Organic  matter,  communi- 
cating a  dark  color  to  the  acid.  These  impurities  do  not  occur  in  the 
C.  P.  acid.  An  acid  to  be  used  in  toxicological  analysis  should  respond 
favorably  to  tl^e  following  tests:  it  should  be  perfectly  colorless,  even 
after  dilution  with  four  volumes  of  water  and  treatment  with  hydrogen  sul- 
phide. The  residue  of  its  evaporation  should  be  insignificant  in  quantity; 
and  when  moistened  with  a  few  drops  of  water,  it  should  give  no  color 
with  solution  of  potassium  ferrocyanide.  At  least  two  fluid  ounces, 
diluted  with  water,  should  give  no  arsenical  stain  in  a  Marsh  apparatus, 
with  pure  zinc,  during  a  heating  of  two  hours  (see  p.  129).  For  cer- 
tain purposes  it  is  necessary  to  have  an  acid  free  from  the  oxides  of 
nitrogen;  such  an  acid  cannot  be  bought,  and  can  only  be  obtained  by 
careful  distillation  of  the  purest  purchasable  acid,  to  which  ammonium 
sulphate  has  been  added,  and  the  collection  separately  of  those  parts  of 
the  distillate  which  give  no  color  with  a  solution  of  brucia. 


Action  on  the  Economy. 

Although  it  is  possible  that  sulphuric  acid,  taken  in  the  diluted  form 
in  sufficient  quantity,  and  during  a  sufficiently  extended  period  of  timer 
may  act  as  a  true  poison  in  diminishing  or  destroying  the  alkaline  reaction 
of  the  circulating  fluids,  we  have  no  record  of  serious  consequences 
resulting  from  its  poisonous  action.  When,  however,  it  comes  in  con- 
tact with  any  tissue,  whether  external  or  internal,  in  the  concentrated  or 
even  moderately  diluted  form,  it  is  one  of  the  most  active  of  corrosives; 
and  cases  are  of  frequent  occurrence  in  which  "  death  or  serious  bodily 
harm"  have  resulted  from  its  being  taken  by  suicides,  or  taken  or  admin- 


92  GENERAL    MEDICAL    CHEMISTRY. 

istered  by  mistake.  It  is  rarely  administered  with  murderous  intent, 
although  it  is  very  frequently  thrown  upon  the  body,  with  design  to 
destroy  the  clothing  or  disfigure  the  person.  The  action  of  the  acid  is 
to  destroy  (to  disorganize)  any  organic  substance  with  which  it  may 
come  in  contact,  and  is  therefor  immediate.  The  majority  of  cases  ter- 
minate fatally,  either  within  a'  few  hours,  from  corrosion  and  perforation 
of  the  oesophagus  and  stomach;  or,  exceptionally,  from  passage  of  the 
,acid  into  the  air-passages,  and  consequent  asphyxia  ;  or,  weeks  or 
months  after  the  ingestion  of  the  acid,  from  starvation,  due  to  destruc- 
tion of  the  mucous  surfaces  of  the  alimentary  canal,  or  closure  of  the 
pyloric  orifice  of  the  stomach  (secondary  effects,  improperly  called 
£i chronic  poisoning"). 

The  treatment  consists  in  neutralizing  the  acid  as  quickly  as  possible, 
by  the  administration  of  slacked  lime,  or  preferably,  of  magnesia,  and  in 
supplying  materials  for  nutrition  per  rectum.  The  administration  of 
such  substances  as  white  of  egg,  oil,  etc.,  is  mere  waste  of  time.  The 
use  of  the  stomach-pump,  when  sulphuric  acid  or  any  corrosive  has  been 
taken,  is  liable  to  make  matters  worse  by  perforating  the  weakened  walls 
of  the  oesophagus  or  stomach. 

The  detection  of  sulphuric  acid  in  the  body  after  death  is  rarely  called 
for  ;  when  it  is,  it  can  only  be  accomplished  by  a  quantitative  analysis. 

"Within  a  few  years  the  practice  of  "  vitriol-throwing"  has  become  quite 
prevalent,  and  the  physician  may  be  called  upon  to  state  whether  stains 
upon  the  clothing  or  person  are  or  are  not  produced  by  this  acid.  Fabrics 
moistened  by  the  acid  are  corroded  and  fall  to  pieces  readily.  If  dyed  of  a 
dark  color,  a  stain  is  produced  which  is  brick-red  when  fresh  and  brown- 
ish when  old  ;  if  not  too  old,  it  is  removed  when  moistened  with  ammo- 
nium hydrate,  which  also  removes  stains  of  hydrochloric  acid  (distinguish- 
.able  by  being  of  a  brighter  red),  but  not  those  of  nitric  acid,  which  are 
brownish  yellow  in  color. 


Hyposulphurous  Acid — S2O3H2, 

Has  not  been  isolated;  the  corresponding  salts,  hyposulphites,  are  used 
in  medicine  and  in  the  arts. 


Pyrosulphuric  Acid. 

Faming  sulphuric  acid — Nordhausen  sulphuric  acid — Disulphuric 
.hydrate — S2O7H2 — contained  in  the  product  known  as  Nordhausen  oil  of 
vitriol,  obtained  by  distillation  of  ferrous  sulphate.  If  the  first  portions 
of  this  distillate  be  separated,  they  become  solid  at  the  ordinary  tem- 
perature, and  by  repeated  fusions,  crystallizations,  and  draining  of  the 
crystals,  a  substance  is  finally  obtained  having  the  above  composition, 
and  fusing  at  35°.  It  forms  salts  called  pyrosulphates  or  disulphates. 

The  commercial  Nordhausen  acid  is  a  brown,  oily  liquid,  fuming  when 
exposed  to  the  air,  solidifying  when  cooled  to  0°,  and  giving  off  SO4Ha 
.and  SO3  when  heated.  It  is  used  in  the  arts,  in  the  manufacture  of 
certain  coloring  matters  (alizarin,  eosin),  and  as  a  solvent  for  indigo 
•(sulphindigotic  acid). 

The  series  of  thionic  acids  have  as  yet  only  a  theoretical  interest. 
Dithionic  or  hypomlphuric  acid — S2O6Ha — is  obtained  as  an  unstable, 


SELENIUM    AND    TELLURIUM.  93 

acid,  syrupy  liquid,  sp.  gr.  1.437,  by  passing  sulphur  dioxide  through 
water  holding  manganese  dioxide  in  suspension,  decomposition  with 
barium  sulphide  and  sulphuric  acid  in  proper  proportion,  and  subsequent 
concentration  in  vacuo. 

Trithionic  acid,  S3O6H2 — obtained  in  a  very  acid,  bitter,  odorless 
solution  by  passing  sulphur  dioxide  through  a  solution  of  potassium  hypo- 
sulphite, decomposing  the  solution  of  potassium  trithionate,  thus  formed 
with  tartaric,  perchloric,  or  hydrofluosilicic  acid,  and  concentrating  the 
solution  in  a  dry  vacuum. 

Tetrathionic  acid,  S4O6H2 — obtained  in  acid,  colorless,  odorless  solu- 
tion, by  decomposing  a  solution  of  its  barium  salt,  prepared  by  the 
action  of  iodine  upon  barium  hyposulphite. 

Pentathionic  acid,  S5O6H2 — obtained  in  aqueous  solution  by  the 
action  of  hydrogen  sulphide  upon  solution  of  sulphurous  acid. 


Compounds  of  Sulphur,  with.  Chlorine,  Bromine,  and  Iodine. 

There  is  but  one  chloride  of  sulphur,  S2C12,  which  is  formed  when  dry 
chlorine  is  passed  through  an  excess  of  sulphur  heated  to  fusion;  the  pro- 
duct is  purified  by  redistillation.  An  oily,  yellow  fluid,  boiling  at  136°, 
having  a  disagreeable,  nauseous  odor  and  fuming  when  exposed  to  the 
air.  It  dissolves  sulphur  abundantly,  and  such  a  solution,  mixed  with 
benzine  or  with  carbon  disulphide,  is  used  in  the  vulcanization  of  rubber. 
Other  chlorides  of 'sulphur  SC12,  and  SC14,  have  been  described,  but  their 
existence  is  problematic. 

A  single  bromide  of  sulphur,  S2Br2,  is  known  as  a  very  unstable  red 
liquid,  boiling  at  215°,  and  formed  by  the  action  of  bromine  upon  sulphur 
dioxide  in  the  presence  of  phosphorus  trichloride. 

An  iodide  of  sulphur,  S2I2,  is  formed  as  a  steel-gray,  crystalline  mass, 
fusible  at  60°,  when  equivalent  quantities  of  sulphur  and  iodine  are 
gently  heated  to  fusion  together,  Sutphwris  iodidum  (U.  S.,  Br.),  or  by 
the  action  of  sulphur  chloride  upon  ethyl  iodide.  Other  ill-defined  iodides 
have  been  described. 


SELENIUM  AND  TELLURIUM. 

Se..                                ...    79.5 
Te 128 

Selenium. — Discovered  in  1817  by  Berzelius;  an  element  existing  in 
very  small  quantities  and  in  limited  distribution  in  combination  with  sul- 
phur, and  as  the  selenides  of  lead,  mercury,  silver,  and  copper.  It  is  capa- 
ble of  existing  in  two  allotropic  forms.  In  its  compounds  it  closely  re- 
sembles sulphur.  Neither  the  element  nor  any  of  its  compounds  has  been 
utilized  in  the  arts  or  in  medicine. 

Tellurium. — One  of  the  least  common  of  the  elements;  discovered  in 
1782,  by  Miiller,  of  Reichenstein.  It  exists  in  nature  uncombined,  and 
as  the  tellurides  of  bismuth,  lead,  silver,  antimony,  nickel,  and  gold. 

It  is  a  solid  body,  having  a  metallic  lustre,  fusible  at  about  500°,  and 
capable  of  distillation  in  an  atmosphere  of  hydrogen.  In  its  chemical 
properties  and  compounds  it  resembles  sulphur  and  selenium.  Its  use  in 
medicine  has  been  attempted,  but  abandoned. 


GENEKAL    MEDICAL    CHEMISTKY. 


III.  NITROGEN  GROUP. 

NITROGEN '. fr . .   14 

PHOSPHORUS P 31 

ARSENIC As 75 

ANTIMONY Sb 122 

The  elements  of  this  group  are  either  trivalent  or  pentavalent.  With 
hydrogen  they  form  non-acid  compounds  composed  of  one  volume  of  the 
element  in  the  gaseous  state  with  three  volumes  of  hydrogen,  the  union 
being  attended  with  a  condensation  of  volume  of  one-half.  Their  hydrates 
are  acids  containing  one,  two,  three,  or  four  atoms  of  replaceable  hydrogen. 

Bismuth,  frequently  classed  in  this  group,  is  excluded,  owing  to  the 
existence  of  the  nitrate  (NO3)3,  Bi.  The  relations  existing  becween  the 
compounds  of  the  elements  of  this  group  are  shown  in  the  following  table: 


Ammonia. 


PH3, 

Hydrogen 
phosphide. 

AsH3, 

Hydrogen 


SbH3, 

Hydrogen 
antimonide. 


N20, 

Nitrogen 
monoxide. 


NO, 

Nitrogen 
dioxide. 


Nitrogen 
trioxide. 

PA, 

Phosphorus 
trioxide. 

As203, 

Arsenic 
trioxide. 


Antimony 
trioxide. 


Nitrogen 
tetroxide. 


Nitrogen 
pentoxide. 

PA 

Phosphorus 
pentoxide. 


Arsenic 
pentoxide. 


Antimony 
pentoxide. 


Hypophosphor- 
OUB  acid. 


P08H3) 

Phosphorous 
acid. 

As03H3 

Arsenious 
acid. 


PO.H,, 

Phosphoric 
acid. 

As04H3, 

Arsenic 
acid. 

Sb04H3, 

Antimonic 
acid. 


PAH,, 

Pyrophosphoric 
acid. 


Pyroarsenic 
acid. 


Pyroantimonic 
acid. 


N03H, 

Nitric 
acid. 

POSH, 

Metaphosphoric 
acid. 

AsO3H, 

Metarsenic 
acid. 


Sb03H, 

Metantimonic 
acid. 


NITROGEN. 


N, 


,14 


First  recognized  as  the  irrespirable  constituent  of  atmospheric  air  by 
Dr.  Rutherford,  of  Edinburgh,  in  1772,  and  by  him  called  aer  mephiticus ; 
subsequently  "  rediscovered  "  by  Scheele  and  Lavoisier,  in  1777,  and  named 


ATMOSPHERIC    AIR.  95 

azote  (d  £0)77)  by  the  latter,  a  name  still  retained  by  French  chemists.  The 
name  nitrogen  (yirpov  yeVecrts)  was  given  subsequently  by  Chaptal. 

It  exists  in  nature  uncombined  as  one  of  the  constituents  of  atmos- 
pheric air,  and  in  combination  in  mineral  substances,  as  well  as  in  some  of 
the  most  important  of  organic  bodies. 

It  is  usually  obtained  from  atmospheric  air  by  removal  of  oxygen,  as 
by  burning  phosphorus  in  a  limited  quantity  of  air,  or  by  passing  a  slow 
current  of  air  over  copper  heated  to  redness.  As  thus  obtained,  nitrogen 
is  contaminated  with  other  constituents  of  air,  carbon  dioxide,  etc.;  to 
obtain  it  in  a  state  of  purity,  recourse  is  had  to  decomposition  of  ammo- 
nium hydrate  by  chlorine  gas,  care  being  had,  however,  that  the  ammoni- 
acal  compound  is  always  present  in  excess,  to  avoid  the  formation  of  the 
highly  explosive  nitrogen  chloride. 

It  is  a  tasteless,  odorless,  colorless  gas,  non-combustible,  and  not  a  sup- 
porter of  combustion  ;  sp.  gr.  0.972 A — 14.041H;  very  sparingly  solu- 
ble in  water  and  in  alcohol. 

Nitrogen  is  very  slow  to  enter  into  combination  with  other  elements, 
and  its  compounds,  once  formed,  are,  as  a  rule,  very  prone  to  decomposi- 
tion, either  sudden  with  explosion,  or  gradual  by  putrefaction.  Nitro- 
gen and  oxygen  are  capable  of  uniting  directly  under  the  influence  of 
electric  discharges.  Direct  union  of  nitrogen  and  hydrogen  does  not 
take  place  under  ordinary  conditions,  but  does  under  the  influence  of 
electric  discharges,  and  during  the  decomposition  of  organic  substances 
containing  nitrogen.  Nitrogen  exerts  no  poisonous  action  when  inhaled  ; 
an  animal  in  an  atmosphere  of  pure  nitrogen  dies  from  simple  lack  of 
oxygen.  This  gas  has  been  put  to  no  use  in  the  arts,  and  is  used  in  the 
laboratory  only  when  an  atmosphere  possessing  the  negative  qualities  of 
nitrogen  is  desired. 

Atmospheric  Air. 

By  the  alchemists,  and  until  the  latter  half  of  the  seventeenth  cen- 
tury, air  was  supposed  to  be  an  elementary  substance,  its  compound  nature 
being  first  recognized  by  Mayow  in  his  Tractatus  quinque  medico-physici, 
published  in  1669.  It  was  not,  however,  until  1770  that  Priestley  re- 
peated and  amplified  the  researches  interrupted  by  the  death  of  Mayow, 
nearly  a  century  before.  Subsequently  the  labors  of  Scheele,  Lavoisier, 
:and  Rutherford  added  largely  to  the  value  of  Priestley's  and  of  Mayow's 
discoveries. 

The  composition  of  atmospheric  air,  under  varying  conditions  of  time, 
location,  temperature,  pressure,  etc.,  has  been  the  subject  of  many  and 
-elaborate  investigations,  which  have  shown  that,  notwithstanding  the 
fact  that  air  is  a  mere  mechanical  mixture,  and  notwithstanding  the  ad- 
ditions to  and  subtractions  from  its  constituent  gases,  to  which  it  is  sub- 
jected by  the  processes  of  animal  and  vegetable  life,  its  composition  is 
nearly  constant;  slight  variations  only  having  been  observed  in  the  quan- 
tity of  gases  present  in  small  amounts.  Leaving  these  out  of  considera- 
tion, air  is  composed  of  :  , 

By  volume.  By  weight. 

Oxygen 20.93 23 

Nitrogen 79.07   77 

The  mean  of  two  hundred  and  thirty-three  analyses  by  Regnault,  of 
air  from  different  locations,  gives  as  the  proportion  of  oxygen  in  volume: 


96  GENERAL    MEDICAL    CHEMISTKY. 

20.953;  the  extremes  being  20.908  and  20.999.  When  air  is  dissolved  in 
water  the  proportion  of  its  constituent  gases  does  not  remain  the  same, 
as  would  be  the  case  were  it  a  definite  compound  ;  but  each  gas  is  dis- 
solved according  to  its  own  solubility  in  water.  As  oxygen  is  more  solu- 
ble than  nitrogen,  dissolved  air  is  richer  in  the  former  gas  than  is  that 
existing  free.  According  to  Bunsen,  .water  saturated  with  air  at  13° 
contains  : 

Oxygen 34.73 

Nitrogen 65.27 

Besides  these  two  main  constituents,  air  contains  about  four  to  live 
thousandths  of  its  bulk  of  other  substances:  vapor  of  water,  carbon  dioxide, 
ammoniacal  compounds,  hydrocarbons,  ozone,  oxides  of  nitrogen,  and 
solid  particles  held  in  suspension. 

Vapor  of  water. — The  proportion  of  vapor  of  water  in  the  atmos- 
phere varies  greatly  at  different  times,  and  at  varying  distances  from 
large  bodies  of  water,  the  air  being  rarely  completely  saturated  with 
water  and  never  entirely  free  therefrom.  Atmospheric  moisture  is  either 
visible,  as  in  fogs,  clouds,  etc.;  or  invisible,  in  solution,  as  it  were.  The 
quantity  of  water  which  air  is  capable  of  thus  holding  in  solution  is 
greater  at  high  than  at  low  temperatures  and  pressures.  Any  sudden  di- 
minution of  temperature  or  pressure  of  an  air  holding  a  large  quantity 
of  moisture  will  bring  about  the  condensation  of  the  moisture  into  drop- 
lets. Dew  and  hoar-frost  are  thus  produced  by  diminution  of  tempera- 
ture during  the  night.  Clouds  are  formed  by  the  air  rising  from  the  sur- 
face, becoming  colder  in  the  upper  atmospheric  layers,  and  being  there 
under  less  barometric  pressure  than  at  the  surface,  where  it  has  become 
charged  with  moisture.  Frequently  also  a  current  of  cold  air,  mixing 
with  air  that  is  warmer  and  charged  with  moisture,  determines  the  forma- 
tion of  clouds  or  fogs,  the  latter  being  simply  clouds  near  the  surface. 

The  actual  amount  of  water  in  air  is  determined  by  passing  a  known 
volume  of  air  through  tubes  filled  with  some  drying  agent,  such  as  cal- 
cium chloride,  whose  increase  of  weight  represents  the  weight  of  water 
contained  in  the  volume  of  air  acted  upon.  The  amount  of  water  in  the 
atmosphere  varies  from  three  to  sixteen  volumes  of  vapor  per  thousand 
of  air;  being,  as  a  rule,  less  in  winter  than  in  summer;  less  in  northern 
latitudes  than  in  the  tropics;  less  in  inland  regions  than  in  the  vicinity 
of  large  bodies  of  water;  less  at  high  altitudes  than  at  the  sea-level;  and 
less  in  cleared  than  in  wooded  districts.  Near  the  sea-shore  the  air  con- 
tains more  moisture  when  the  wind  blows  from  the  sea  than  when  it 
I  blows  in  the  opposite  direction. 

The  degree  of  dampness  of  the  air  does  not  depend  upon  the  abso- 
lute quantity  of  watery  vapor  which  it  contains,  but  upon  the  propor- 
tion existing  between  that  quantity  and  the  amount  of  water  which  the 
air  could  hold  if  saturated  with  moisture  at  the  same  temperature  and 
pressure;  a  proportion  which  is  known  as  the  fraction  of  saturation  of 
the  air;  or  its  hygrometric  condition^  determined  by  instruments  called 
hygrometers,  hygroscopes,  or  psychrometers.  While  the  air  in  winter  is 
usually  more  damp  than  in  summer,  it  contains  an  absolute  quantity  of 
water,  less  in  the  winter  than  in  the  summer;  but,  being  in  the  former 
season  more  nearly  saturated,  its  tendency  to  precipitate  the  moisture  is 
greater;  while  during  the  summer  months,  on  th£  other  hand,  the  air, 
although  containing  more  aqueous  vapor  than  in  winter,  is,  at  the  reigning 


ATMOSPHERIC   AIK.  97 

/ 

temperature,  less  nearly  saturated,  and  consequently  more  capable  of  ex- 
erting a  drying  influence  by  taking  up  a  further  quantity  of  water. 

The  deo-ree  of  saturation  influences  the  body  temperature  materially 
by  impeding  or  promoting  evaporation  from  the  surface,  which  is 
greater  the  less  near  the  air  is  to  its  point  of  saturation.  Heat  is,  there- 
for, more  oppressive  when  the  air  is  moist  than  when  it  is  dry.  Life  may 
be,  for  the  same  reason,  maintained  at  a  much  higher  temperature  if  the 
air  be  dry  than  if  it  be  moist. 

When  dwellings  are  heated  artificially  in  winter,  the  air  should  be 
charged  with  vapor  of  water  by  placing  a  pan  containing  water  on  the 
stove  or  in  the  air-box  of  the  furnace;  for,  although  the  actual  amount  of 
moisture  is  not  diminished,  the  degree  of  saturation  is,  and  the  air  in 
consequence  becomes  dry  and  close  unless  vapor  of  water  be  added. 

Carbon  dioxide. — The  quantity  of  atmospheric  carbon  dioxide  varies 
from  three  to  six  parts  in  ten  thousand  by  volume,  the  average  in  the 
country  being  four  in  ten  thousand.  The  amount  is  greater  in  cities,  or 
in  the  neighborhood  of  natural  or  artificial  sources  of  the  gas,  than  in  the 
open  country;  on  land  greater  during  the  night  than  during  the  day. 
At  sea  the  reverse  is  the  case,  the  difference  being  due  to  the  removal 
of  carbon  dioxide  by  plants  under  the  influence  of  sunlight  in  the  one 
case,  and  to  the  greater  solubility  of  the  gas  in  cold  than  in  warm  water  in 
the  second.  The  quantity  is  also  greater  in  the  atmospheric  layers 
nearest  the  earth  than  in  those  at  greater  elevations  (see  p.  237). 

Otlier  substances  contained  in  air — Ammoniacal  compounds. — Air 
contains  small  quantities  of  ammoniacal  salts,  carbonate,  nitrate,  and 
nitrite,  the  products  of  the  decomposition  of  animal  and  vegetable  sub- 
stances. They  are  present  in  very  small  amount,  not  exceeding  a  few 
millionth*,  and  are  taken  up  by  plants,  by  which  they  are  assimilated. 
Frequently  in  cold,  dry  weather,  ammonium  nitrate  will  be  found  con- 
densed as  a  snow-white  crust  on  the  sides  of  ventilators  from  stables,, 
urinals,  etc. 

Hydrocarbons. — In  the  air  of  cities  undetermined  hydrocarbons  have 
been  detected  to  the  maximum  extent  of  0.0001  part  by  volume.  In  the 
air  of  swampy  places  the  proportion  is  greater  (see  Marsh-gas). 

Nitric  and  nitrous  acids  exist  in  combination,  usually  with  ammonia. 
They  are  produced  either  by  the  oxidation  of  combustible  substances,  or 
by  direct  union  of  nitrogen  with  vapor  of  water  under  the  influence  of 
electric  discharges.  Rain-water  falling  during  thunder-showers  contains 
comparatively  large  quantities  of  ammonium  nitrate. 

Solid  particles  in  suspension  in  air  are  exceedingly  diverse  in  their 
nature.  Inorganic  salts,  notably  chloride  of  sodium,  are  especially  abun- 
dant in  air  in  the  vicinity  of  salt  water,  and  rarely  is  air  so  free  from  this 
salt  that  the  flame  of  a  Bunsen  burner,  when  examined  spectroscopically, 
does  not  show  the  sodium  lines. 

Minute  particles  of  the  most  heterogeneous  substances  float  in  air  as 
dust,  and  become  visible  in  the  path  of  a  ray  of  sunlight.  The  continued 
inhalation  of  air  containing  large  quantities  of  such  solid  particles  in  sus- 
pension may  cause  severe  pulmonary  disorder  by  mere  mechanical  irrita- 
tion, and  apart  from  anv  poisonous  quality  in  the  substance  ;  such  is  the 
case  with  the  air  of  carpeted  ball-rooms,  and  of  the  workshops  of  certain 
trades,  furniture-polishers,  metal-filers,  etc. 

Air  always  contains  varying  quantities  of  vegetable  germs,  to  which 
the  phenomena  of  the  so-called  spontaneous  generation  are  due,  and 
concerning  whose  action  in  the  propagation  of  disease  so  much  has  been 
7 


98  GENERAL    MEDICAL    CHEMISTRY. 

written  and  so  little  is  known.  By  miasms  are  understood  certain  ill-de- 
fined, putrescible,  volatile,  or  solid  substances  contained  in  air  and  evolved 
from  unhealthy  localities. 

The  air  of  confined  spaces  in  which  human  beings  or  animals  are  re- 
spiring is  not  only  deteriorated  by  the  production  of  carbon  dioxide  and 
consumption  of  oxygen  (see  p.  -240),  bujfc  also  by  the  discharge  into  it  of 
particles  of  organic  matter  prone  to  putrefaction.  These  emanations,  even 
when  derived  from  healthy  persons,  soon  render  the  air  foul,  and  their 
removal  from  spaces  in  which  many  people  are  congregated  is  one  of  the 
chief  functions  of  ventilation. 


Ammonia. 

Hydrogen  nitride — NH3 — does  not  exist  as  such  in  nature. 

Obtained  by  decomposition  of  ammonium  chloride,  sulphate,  or  car- 
bonate, by  slightly  heating  with  dry  slacked  lime.  In  the  laboratory, 
by  heating  aqua  ammonias,  and  drying  the  gas  by  passing  it  through  a  tube 
containing  quicklime.  At  ordinary  temperatures  and  pressure  it  is  a 
colorless  gas,  having  a  penetrating  odor  ;  irritating  to  the  eyes  and  air- 
passages  ;  sp.  gr.  0.589 A — 8.5H.  ;  exceedingly  soluble  in  water,  with 
which  it  enters  into  combination  (see  p.  409);  at  — 40°  at  the  ordinary 
pressure,  or  at  10°  under  a  pressure  of  six  atmospheres,  it  forms  a  color- 
less, mobile  liquid,  which  boils  at  — 33.7°;  and  at  —75°  forms  a  colorless, 
transparent,  crystalline  mass,  having  but  little  odor. 

Ammonia  is  formed  with  difficulty  by  the  union  of  its  elements  (see 
p.  95).  When  a  mixture  of  hydrogen  and  one  of  the  oxides  of  nitrogen 
is  passed  over  heated  platinum-sponge,  reduction  occurs,  with  formation 
of  water  and  ammonia.  If  a  mixture  of  sulphuric  and  nitric  acids  in 
proper  proportion  be  poured  upon  zinc,  there  is  no  evolution  of  gas, 
although  the  zinc  dissolves.  In  this  reaction  the  hydrogen  reduces  the 
nitric  acid  with  formation  of  an  ammoniacal  compound. 

Most  organic  substances  containing  nitrogen  yield  an  ammoniacal 
compound,  either  by  dry  distillation,  putrefaction,  or  the  action  of  vapor 
of  water,  or  of  the  caustic  alkalies. 

Ammonia  is  decomposed — two  volumes  yielding  one  volume  of  nitrogen 
and  three  of  hydrogen — by  being  heated  to  redness,  or  by  the  passage  of 
the  electric  spark  through  it;  by  chlorine  or  bromine,  with  liberation 
of  nitrogen  (see  Nitrogen  Chloride);  by  iodine  with  formation  of  ex- 
plosive compounds  of  iodine  and  nitrogen;  by  the  alkaline  hypochlorites 
and  hypobromites. 

Under  ordinary  conditions,  ammonia  is  neither  a  supporter  of  combus- 
tion nor  combustible;  it  may  be  made  to  burn,  however,  in  an  atmosphere 
of  oxygen,  and  mixtures  of  ammonia  with  oxygen,  with  nitrogen  mon- 
oxide, or  with  nitrogen  dioxide,  explode  when  fired  by  the  passage 
through  them  of  the  electric  spark. 

Potassium,  when  heated  in  an  atmosphere  of  ammonia,  replaces  an 
atom  of  hydrogen  with  formation  of  potassium  amide,  KH3N.  With 
silver  nitrate,  ammonia  forms  two  compounds,  differing  from  each  other 
in  the  temperatures  at  which  they  are  formed,  and  in  the  readiness  with 
which  they  give  off  ammonia.  With  the  acids  ammonia  unites  directly 
to  form  ammoniacal  salts  (see  p.  408). 

When  inhaled,  ammonia  produces  violent  irritation  of  the  respiratory 


NITROGEN    MONOXIDE.  99 

organs,  and  a  sense  of  suffocation.  Care  should  be  had  in  administering 
the  vapor  in  fainting-fits,  etc.,  as  cases  are  recorded  in  which  death  has 
resulted  from  the  use  of  too  liberal  doses. 


Nitrogen  Monoxide. 

Nitrons  oxide — Laughing-gas — Nitrogen  protoxide,  N2O. — Discov- 
ered in  1766,  by  Priestley;  further  studied  by  Sir  Humphrey  Davy,  who 
observed  its  effects  upon  the  economy  when  inhaled. 

Prepared  by  decomposing  ammonium  nitrate  by  heat: 

N03(NH4)=NaO+2H30. 

If  the  gas  be  desired  pure — as  it  should  always  be  when  used  as  an  anaes- 
thetic— the  ammonium  salt  must  be  pure  and  dry,  and,  especially,  free 
from  chloride,  lest  the  gas  be  contaminated  with  chlorine.  The  salt 
should  be  heated,  not  too  quickly,  and  the  temperature  maintained  be- 
tween 210°  and  250°.  Below  the  lower  temperature  the  decomposition 
does  not  occur,  and  the  salt  sublimes;  while,  at  temperatures  above  250°, 
nitrogen  dioxide  and  nitrogen  trioxide  are  also  formed.  As  an  additional 
precaution,  the  gas  should  be  caused  to  bubble  through  solutions  of 
sodium  hydrate  and  of  ferrous  sulphate,  to  arrest  any  higher  oxides  of 
nitrogen  which  may  be  formed. 

Nitrogen  monoxide  is  a  colorless,  odorless  gas,  having  a  sweetish 
taste;  sp.  gr.  1.527A — 22H;  somewhat  soluble  in  water,  more  so  in 
alcohol.  Under  a  pressure  of  thirty  atmospheres  at  0°,  it  forms  a  colorless, 
mobile  liquid,  which  boils  at  —87.9°,  and  solidifies  at  —100°.  The 
liquefied  gas,  in  suitable  wrought-iron  vessels,  is  obtainable  from  dental 
depots,  and  is  used  by  dentists  as  a  convenient  source  of  the  gas  for  use 
as  an  anaesthetic. 

Nitrogen  monoxide  is  decomposed  by  a  red  heat,  or  by  the  continued 
passage  of  the  induction  spark.  It  is,  after  oxygen,  the  best  supporter 
of  combustion  known,  being  readily  decomposed  into  a  mixture  of  oxygen 
and  nitrogen,  in  which  the  former  gas  is  in  larger  proportion  than  in  at- 
mospheric air  (36.36  per  cent,  by  weight). 

The  action  of  this  gas  upon  the  economy  is  of  medical  interest,  from 
its  use  as  an  anaesthetic,  and  in  connection  with  the  history  of  anaesthesia. 
Although,  owing  to  the  readiness  with  which  nitrogen  monoxide  is  de- 
composed into  its  constituent  elements,  and  the  nature  and  relative  pro- 
portions of  these  elements,  it  is  capable  of  maintaining  respiration  longer 
than  any  gas  or  mixture  of  gases,  except  oxygen  or  air;  an  animal  will 
live  for  a  short  time  only  in  an  atmosphere  of  pure  nitrous  oxide.  When 
inhaled  diluted  with  air,  it  produces  the  effects  first  observed  by  Sir 
Humphrey  Davy  in  1799:  first  an  exhilaration  of  spirits,  frequently  ac- 
companied by  laughter,  and  a  tendency  to  muscular  activity,  the  patient 
sometimes  becoming  aggressive;  afterward  there  is  loss  of  consciousness 
and  complete  anaesthesia.  It  has  been  much  used,  by  dentists  especially, 
as  an  anaesthetic  in  operations  of  short  duration,  and  in  one  or  two  in- 
stances anaesthesia  has  been  maintained  by  its  use  for  nearly  an  hour. 

A  solution  in  water  under  pressure,  containing  five  volumes  of  the  gas, 
is  sometimes  used  for  internal  administration. 


100  GENERAL    MEDICAL    CHEMISTRY. 


Nitrogen  Dioxide. 

Nitric  oxide  —  NO.  —  Discovered  by  Hales  in  1772. 
Prepared  by  the  action  of  copper  upon  nitric  acid: 

'  '  ' 
3Cu+SN03H=:3 


At  first  the  flask  in  which  the  action  takes  place  is  filled  with  brown 
fumes,  which  gradually  disappear;  the  gas  is  not  collected  until  it  has 
become  colorless;  the  acid  used  should  not  be  too  concentrated,  and  should 
not  be  allowed  to  become  heated. 

It  is  a  colorless  gas,  whose  taste  and  odor  are  unknown;  sp.  gr. 
1.039A  —  15H;  very  sparingly  soluble  in  water;  more  soluble  in  alcohol. 

When  mixed  with  oxygen  or  air,  it  immediately  unites  with  oxvgen  to 
form  the  tetroxide,  which  appears  as  a  reddish  brown  gas.  When  passed 
through  a  solution  of  ferrous  sulphate,  it  is  absorbed  by  the  liquid,  to 
which  it  communicates  a  dark  brown  or  black  color. 

Although  containing  a  greater  proportion  of  oxygen  than  air  or  nitro- 
gen monoxide,  it  is  not  as  good  a  supporter  of  combustion  as  either  of 
those  gases;  although  phosphorus  burns  in  it  brilliantly,  and  the  alkaline 
metals  unite  with  its  oxygen  with  incandescence  when  heated  in  its 
presence. 

Nitrogen  Trioxide. 

Nitrous  anhydride  —  N2O3.  —  A  substance  not  yet  isolated  in  a  state 
of  purity,  the  purest  yet  obtained  still  containing  about  five  per  cent,  of  the 
tetroxide,  from  which  it  is  obtained  by  decomposing  with  water  at  a  low 
temperature: 

4NO,  +  H20  =  2N03H  +  N2O8. 

At  ordinary  temperatures  it  is  a  gas,  whose  properties  are  masked  bv 
the  presence  of  the  tetroxide;  below  the  freezing-point  of  water  it  is  a 
dark  indigo-blue  liquid,  which,  boiling  at  about  0°,  suffers  partial  decom- 
position. 

Nitrogen  Tetroxide. 

Nitrogen  peroxide  —  Hyponitric  acid  —  Nitrous  fumes  —  NO2.  —  Formed 
whenever  nitrogen  trioxide  comes  in  contact  with  oxygen.  More  read- 
ily, and  in  a  condition  of  greater  purity,  by  heating  dry  lead  nitrate  to 
redness,  when  nitrogen  tetroxide  is  given  off  and  lead  oxide  remains. 

Formed  also  indirectly  when  a  metal  is  dissolved  in  nitric  acid;  and 
directly  when  nitric  acid  is  brought  in  contact  with  a  platinum  surface 
heated  to  redness. 

This  substance  is  remarkable  for  assuming  when  pure  the  three  condi- 
tions of  matter  within  a  comparatively  small  range  of  temperature;  above 
22°  it  is  a  gas;  between  that  temperature  and  —9°  it  is  a  liquid;  and  below 
that  a  solid.  The  color  of  the  liquid  varies  with  the  temperature,  being 
of  a  light  brown  color  at  ordinary  temperatures,  and  darkening  as  the 
point  of  solidification  is  approached.  Nitrogen  tetroxide  is  decomposed 


NITROGEN    PENTOXIDE.  101 

by  water  with  the  formation  of  nitrous  and  nitric  acids,  and  by  the  hy- 
drates of  the  alkaline  and  alkalo-earthy  metals,  with  formation  of  a  nitrite 
and  a  nitrate. 

Action  on  the  Economy. 

The  brown  fames  given  oil  during-  many  processes,  in  which  nitric 
acid  is  decomposed,  consist  largely  of  nitrogen  tetroxide,  and  are  not 
only  offensive,  but  dangerous  to  life.  All  such  operations,  when  carried 
on  on  a  small  scale,  as  in  the  laboratory,  should  be  conducted  under  a 
hood  or  some  other  arrangement,  by  which  the  fumes  are  carried  into  the 
open  air;  when,  in  industrial  processes,  the  volume  of  gas  formed  becomes 
such  as  to  be  a  nuisance  when  discharged  into  the  air,  it  should  be  ab- 
sorbed, either  by  utilizing  it  in  the  manufacture  of  sulphuric  acid,  or  by 
causing  it  to  be  absorbed  by  water  or  an  alkaline  solution. 

An  atmosphere  contaminated  with  brown  fumes  is  more  dangerous 
than  one  containing  chlorine,  as  the  presence  of  the  latter  is  more  imme- 
diately annoying,  while  the  former  only  produces  its  full  effects  some  time 
after  inhalation. 

Quite  a  number  of  fatal  cases  are  recorded,  usually  resulting  from  the 
spilling  of  nitric  acid  and  attempts  on  the  part  of  the  victim  to  pre- 
vent or  repair  damage  caused  thereby.  At  first  there  is  only  coughing, 
and  it  is  only  two  to  four  hours  later  that  a  difficulty  in  breathing  is  feft, 
death  occurring  in  ten  to  fifteen  hours.  At  the  autopsy  the  lungs  are 
found  to  be  extensively  disorganized  and  filled  with  black  fluid. 

Even  air  containing  small  quantities  of  brown  fumes,  if  breathed  for 
a  long  time,  produces  chronic  disease  of  the  respiratory  organs.  To  pre- 
vent such  accidents,  thorough  ventilation  in  locations  where  brown  fumes 
are  liable  to  be  formed  is  imperative.  In  cases  of  spilling  nitric  acid,  safety 
is  to  be  sought  in  retreat  from  the  apartment  until  the  fumes  have  been 
replaced  by  pure  air  from  without. 


Nitrogen  Pentoxide. 

Nitric  anhydride,  N2O&. — Obtained  by  Deville,  by  decomposing  dry 
silver  nitrate  with  dry  chlorine,  the  operation  being  aided  by  gentle  heat, 
and  conducted  in  an  apparatus  made  entirely  of  glass,  with  ground  joints; 
or,  more  readily,  by  the  removal  of  water  from  fuming  nitric  acid  by  the 
action  of  phosphorus  pentoxide. 

It  forms  prismatic  crystals,  which  fuse  at  30°,  and  boil  at  47°.  It  takes 
up  water  with  great  eagerness,  and  gives  off  white  fumes  when  exposed 
to  the  air,  the  result  of  its  combination  with  water  being  nitric  acid. 
Even  when  kept  in  sealed  tubes  at  low  temperatures,  it  decomposes  slowly 
into  oxygen  and  nitrogen  tetroxide,  the  pressure  of  the  gases  formed  being 
often  sufficient  to  fracture  the  glass,  although  the  pentoxide  is  not,  strictly- 
speaking,  explosive.  The  decomposition  is  hastened  by  the  action  of  heat 
or  of  light.  Most  substances  which  unite  readily  with  oxygen  remove 
that  element  from  the  pentoxide,  the  action  being  attended  with  the  ap- 
pearance of  light  and  heat. 


102  GENERAL    MEDICAL    CHEMISTRY. 

Nitrogen  Acids. 

Three  of  these  are  known  to  exist,  either  free  or  in  combination: 

Hyponitrous  acid,         Nitrous' acid,        Nitric  acid, 

NOH,  N02H,         N03H, 

corresponding  to  the  three  oxides,  which  contain  for  two  atoms  of  nitro- 
gen an  uneven  number  of  atoms  of  oxygen: 

N20  +H20=2NOH. 
N203  +  H20=2N02H. 
NaOB+H20=:2N08H. 

Syponitrous  acid,  NOH. — Obtained  by  E.  Divers,  in.  1871,  as  its  sil- 
ver salt,  by  the  action  of  nascent  hydrogen  on  sodium  nitrate,  and  precip- 
itation with  silver  nitrate;  and  in  aqueous  solution,  by  decomposing  the 
silver  salt  with  the  proper  quantity  of  hydrochloric  acid;  as  yet  only  of 
theoretical  interest. 

Nitrous  acid,  NO2H. — Although  this  acid  has  not  yet  been  isolated 
in  a  state  of  purity,  there  exist,  corresponding  to  it,  a  series  of  well-defined 
salts  called  nitrites,  having  the  composition  NO2M'  or  (NO2)2M". 

Nitric  Acid. 

Acidum  nitricum  (  IT.  $.,  JBr.) — Aquafortis — NO3H. — Known  to  the 
earlier  alchemists  as  aqua  prtma,  aquafortis,  or  spirits  of  nitre.  Its  true 
nature  was  first  recognized  by  Cavendish,  in  1784.  It  does  not  exist  free 
in  nature,  but  is  abundant  and  widely  disseminated  in  its  salts,  the  nitrates. 

Nitric  acid  is  formed,  naturally  and  artificially,  in  the  process  known 
as  nitrification  (q.  v.),  by  the  decomposition  of  nitrogenized  organic  ma- 
terials. It  is  also  formed  by  the  passage  of  electric  discharges  through  a 
mixture  of  nitrogen  and  oxygen,  a  formation  which  takes  place  naturally 
in  the  atmosphere,  to  a  limited  extent.  Under  certain  conditions,  it  is  also 
formed  by  the  action  of  air  upon  ammonia,  and  by  the  oxidation  of  nitro- 
gen or  of  ammonia  by  ozone. 

The  nitric  acid  used  in  the  arts  is,  however,  exclusively  obtained  by 
the  decomposition  of  the  nitrates  of  sodium  and  of  potassium  by  sulphuric 
acid: 

NO,Na + S04H2 = SO4HNa + NO3H, 

the  decomposition  being  conducted  by  the  aid  of  heat  in  cast-iron  vessels, 
from  which  the  vapors  are  conducted  through  earthenware  bottles  in  which 
the  nitric  acid  condenses.  The  acid  so  formed  is  still  largely  charged  with 
brown  fumes,  chlorine,  and  sulphuric  acid,  from  which  it  is  separated  by 
heating  to  80°,  and  by  rectification  over  lead  nitrate. 

The  pure  acid,  having  the  composition  NOSH,  is  a  colorless,  rather 
heavy  liquid;  sp.  gr.  1.52;  boils  at  86°;  solidifies  at  —40°;  gives  off  white 
fumes  in  damp  air;  has  a  strong  acid  taste  and  reaction,  and  destroys 
organic  matters.  The  specific  gravity  and  the  boiling-point  of  acids  of 
less  strength  differ  with  the  amount  of  true  nitric  acid  which  they  con- 
tain; the  following  table,  partly  from  Willm's  article  in  Wurtz'  "Diet.  d. 
Chimie,"  arid  partly  from  Kolb,  indicates  these  variations. 


NITRIC    ACID. 


103 


QUANTITY  OF  TRUE  NO3H  IN  NITRIC  ACIDS  OF  DIFFERENT 

DENSITIES. 


Density. 

Degree  Baum& 

Per  cent,  water. 

Per  cent.  NO3H. 

Boiling-point. 

1.522 

49.3 

100.00 

86° 

1.486 

46.5 

11.25 

88.75 

99° 

1.452 

45.0 

22.22 

77.78 

115° 

1.420 

42,6 

30.00 

70.00 

120° 

1.390 

40.4 

36.36 

63.64 

119° 

1.361 

38.2 

41.67 

58.33 

117° 

1.338 

36.5 

46.16 

53.84 

1.315 

34.5 

50.00 

50.00 

113° 

1.297 

33.2 

53.33 

46.67 

1.277 

31.4 

56.25 

43.75 

1.260 

29.7 

58.82 

41.18 

1.245 

28.4 

61.11 

38.89 

1.232 

27.2 

63.16 

36.84 

1.219 

25.8 

65.00 

35.00 

1.207 

24.7 

66.67 

33.33 

ios° 

1.197 

23.8 

68.18 

31.82 

1.188 

22.9 

69.56 

30.44 

1.180 

22.0 

70.83 

29.17 

1.173 

21.0 

72.00 

28.00 

1.166 

20.4 

73.08 

26.92 

1.160 

19.9 

74.07 

25.93 

1.155 

19.3 

75.00 

25.00 

about  16-4° 

1.138 

17.6 

77.00 

23.00 

1.120 

15.4 

80.00 

20.00 

1.101 

13.1 

82.56 

17.44 

1.089 

11.8 

85.00 

15.00 

1.068 

9.4 

88.57 

11.43 

1.022 

2.8 

96.00 

4.00 

1.010 

1.4 

98.00 

2.00 

It  will  be  observed  that  the  boiling-point  at  first  increases  and  then  dimin- 
ishes with  dilution.  If  a  strong  acid  be  distilled,  the  boiling-point  will 
gradually  increase  until  it  reaches  about  123°,  when  it  will  remain  con- 
stant, the  density  of  distilled  and  distillate  at  this  point  being  about  1.42; 
if,  on  the  other  hand,  a  weaker  acid  be  taken  originally,  the  boiling-point 
will  rise  until  it  reaches  the  same  point,  where  it  remains  constant. 

If  heated  to  redness,  the  vapor  of  nitric  acid  is  decomposed  into  nitro- 
gen tetroxide,  water,  and  oxygen.  The  same  change  takes  place  when 
the  acid  is  exposed  to  light  and  air  at  ordinary  temperatures;  it  is  from 
this  cause  that  nitric  acid  in  partially  filled  bottles,  exposed  to  the  light, 
assumes  a  yellowish  tinge.  Nitric  acid  gives  up  its  oxygen  readily,  and 
is  thus  a  valuable  oxidizing  agent.  Most  of  the  metalloids  are  oxidized 
by  it,  and  lower  are  converted  into  higher  stages  of  oxidation.  It  also 
oxidizes  many  organic  substances,  and  with  others  forms  products  of  sub- 
stitution. Copper,  silver,  and  mercury  are  dissolved  in  nitric  acid,  espe- 


104  GENERAL    MEDICAL    CHEMISTRY. 

cially  under  the  influence  of  heat,  with  formation  of  nitrates  and  evolution 
of  nitrogen  dioxide,  which,  combining1  with  atmospheric  oxygen,  forms 
brown  fumes: 

4NO3H+3Ag=3NO3Ag+NO  +  2H2O. 

The  action  between  nitric  acid  and  ir6"n  is  peculiar;  a  weak  acid  dissolves 
the  metal  readily,  with  evolution  of  brown  i'umes;  but  a  strong  acid  not 
only  does  not  dissolve  it,  but  renders  it  passive,  so  that  when  it  is  trans- 
ferred from  the  strong  to  a  weak  acid  no  action  takes  jplace  until  the  pas- 
sive condition  of  the  iron  is  destroyed  by  touching  it  with  a  piece  of  plati- 
num wire,  or  by  other  means.  When  nitrogen  dioxide  and  nitric  acid 
come  together  they  decompose  each  other,  with  formation  of  the  tetroxide: 

2N03H+NO=3N02  +  II30, 

the  tetroxide  boing  in  turn  decomposed,  in  presence  of  the  water  of  the 
acid,  into  nitric  acid  and  the  trioxide: 

4NO2  +  H2O=2NO3H-fN2O3, 

the  latter  being  dissolved  in  the  acid,  to  which  it  communicates  a  yellow, 
brown,  or  green  color.  An  acid  so  charged  with  the  trioxide,  sometimes 
called  nitrosonitric  acid,  is  obtained  by  acting  upon  nitric  acid,  with  cop- 
per or  iron,  or  preferably,  by  connecting  the  terminals  of  one  or  more  cells 
of  a  Grove  battery,  and  removing  the  acid  from  the  porous  cup  after  the 
action  has  continued  for  half  an  hour. 

Nitric  acid  oxidizes  hydrochloric  acid  when  brought  in  contact  with 
it,  with  liberation  of  free  chlorine  or  of  compounds  of  chlorine,  oxygen,  and 
hydrogen.  A  mixture  of  three  parts  of  hydrochloric  acid  with  one  part 
of  nitric  acid,  both  of  commercial  strength,  is  a  reddish  yellow  liquid, 
known  as  aqua  regia,  which,  in  the  presence  of  bodies  capable  of  uniting 
with  chlorine,  is  a  source  of  that  element  in  the  nascent  state. 

Nitric  acid  occurs  in  commerce  and  in  pharmacy  in  the  following 
forms: 

Commercial,  a  yellowish  liquid,  contaminated  with  oxides  of  nitro- 
gen, hydrochloric  acid,  arsenic  and  other  impurities,  should  never  be 
used  medicinally,  or  for  any  but  rough  chemical  purposes.  It  is  of  two 
strengths;  single  aquafortis,  specific  gravity  about  1.25,  and  double  aqua 
fort  is,  specific  gravity  about  1.4. 

Fuming. — A  reddish  yellow  fluid,  of  sp.  gr.  1.525,  highly  charged 
with  nitrogen  trioxide  (and  tetroxide  ?),  more  or  less  free  from  impurities, 
according  to  the  care  exercised  in  its  manufacture.  Used  as  an  oxidizing 
agent. 

C.  P.,  or  chemically  pure — perfectly  colorless,  sp.  gr.  1.522.  A  por- 
tion evaporated  on  platinum  should  leave  no  residue.  When  diluted 
with  two  volumes  of  distilled  water  it  should  give  no  cloudiness  with 
barium  chloride  (sulphuric  acid),  or  with  silver  nitrate  (chlorine).  Chloro- 
form, when  shaken  with  the  diluted  acid,  should  not  be  colored,  even 
after  the  addition  of  a  few  drops  of  solution  of  hydrogen  sulphide  (iodine). 
Solution  of  potassium  permanganate  should  not  be  decolorized  when 
added  to  the  dilute  acid  (oxides  of  nitrogen).  When  evaporated  over 
the  water-bath  to  small  bulk,  the  residue,  diluted  with  water,  should  not 
give  any  colored  precipitate  when  treated  with  hydrogen  sulphide 
(metals). 


ACTION    ON    THE    ECONOMY.  105 

For  analytical  processes  only  an  acid  responding  to  these  tests,  or  a 
fuming  acid  responding  to  all  except  those  for  the  oxides  of  nitrogen, 
should  be  used.  An  impure  acid  may  be  purified  by  distilling  and  reject- 
ing the  first  quarter  of  its  bulk,  adding  to  the  remainder  excess  of  silver 
nitrate  and  barium  nitrate,  and  distilling  in  an  apparatus  of  glass. 

Acidum  nitricum  ( IT.  $.,  j5r.). — An  acid  of  sp.  gr.  1.42,  containing 
70$  NO3H,  and  free  from  impurities  other  than  water. 

Acidiun  nitricum  dilutum  ( U.  $.,  JBr.),  the  last  mentioned,  diluted 
with  water  to  sp.  gr.  1.068  =  11.43$  NO3H  (U.  JS.)9  or  sp.  gr.  1.101  = 
17.44$  N03H  (_£V.). 

Nitric  acid  should  be  kept  in  bottles  completely  filled  and  protected 
from  the  light. 

Ancdysis — The  presence  of  nitric  acid,  or  of  a  nitrate,  may  be  detected 
by  the  following  tests: 

First. — Add  to  the  liquid  an  equal  volume  of  concentrated  sulphuric 
acid,  cool,  float  upon  the  surface  of  the  mixture  a  small  quantity  of  a 
solution  of  ferrous  sulphate;  if  nitric  acid  or  a  nitrate  be  present,  the 
lower  layer  is  after  a  time  colored,  beginning  at  the  top,  black,  brown, 
or  reddish  purple,  according  to  the  quantity  of  acid  present. 

Second. — Boil  in  a  test-tube  a  small  quantity  of  hydrochloric  acid 
containing  enough  solution  of  sulphincligotic  acid  to  communicate  a  blue 
color;  if  now  nitric  acid  or  a  solution  of  a  nitrate  be  added,  and  the  mix- 
ture again  boiled,  the  color  is  discharged. 

Third. — If  acid,  neutralize  with  an  alkali,  evaporate  to  dryness,  add 
to  the  residue  a  few  drops  of  sulphuric  acid  and  a  crystal  of  brucia;  a  red 
color  is  communicated  to  the  alkaloid  by  nitric  acid.  In  place  of  brucine, 
sulphanilic  acid  may  be  used. 

Fourth. — Heat  the  suspected  solution  (to  which,  in  the  case  of  a  nitrate, 
concentrated  sulphuric  acid  has  been  added)  with  copper  turnings  in  a 
test-tube;  if  nitric  acid  be  present,  brown  fumes  will  appear,  best  visible 
by  looking  into  the  mouth  of  the  tube. 

All  neutral  nitrates  are  soluble  in  water;  some  so-called  basic  salts  are 
insoluble,  as  bismuthyl  nitrate,  NO3  (BiO). 


Action  on  the  Economy. 

Nitric  acid  cannot  be  said  to  be  a  true  poison,  for,  although  most  of 
the  nitrates  exert  a  poisonous  action  when  taken  internally,  that  action 
seems  to  be  due  more  to  the  metal  than  to  the  acid  radical.  Nitrates 
have  also  been  found  to  be,  although  in  very  small  quantity,  normal 
constituents  of  the  urine. 

The  acid  is,  however,  one  of  the  most  powerful  of  corrosives;  any 
animal  tissue  with  which  it  comes  in  contact  is  immediately  disintegrated; 
a  yellow  stain,  afterward  turning  to  dirty  brownish,  or,  if  the  action  be 
prolonged,  an  eschar,  is  formed.  When  taken  internally  its  corrosive 
action  is  the  same  as  that  which  follows  its  application  to  the  cutaneous 
surface,  but,  owing  to  the  function  of  the  parts,  is  followed  by  more 
serious  results.  As  is  the  case  with  the  other  mineral  acids,  it  is  rarely 
administered  with  intent  to  murder,  but  is  frequently  taken  by  suicides, 
or  by  mistake  by  children  or  inebriates.  The  symptoms  following  its  in- 
gestion  are  the  same  as  those  appearing  with  the  other  corrosive  acids, 
with  the  exception  that  the  mouth  and  any  other  parts  with  which  the 
acid  may  have  come  in  contact,  as  well  as  shreds  of  detached  mucous 


106  GENERAL    MEDICAL    CHEMISTRY. 

membrane  in  the  vomited  matters,  are  stained  yellow,  which  is  not  the 
case  when  sulphuric  or  hydrochloric  acid  has  been  taken. 

The  treatment  is  the  same  as  in  corrosion  by  sulphuric  or  hydrochloric 
acid,  i.  e.,  neutralization  by  magnesia,  or,  failing  that,  by  alkalies,  as 
rapidly  as  possible,  and  a  subsequent  sustaining  treatment. 


Compounds  of  Nitrogen  with  Elements  of  the  Chlorine  Group. 

Nitrogen  chloride,  NC13,  obtained  by  the  action  of  chlorine  gas,  in 
excess,  upon  ammonia  or  upon  an  ammonium  compound,  or  by  the  elec- 
trolysis of  a  strong  solution  of  ammonium  chloride;  usually,  by  confining 
chlorine  over  a  solution  of  ammonium  chloride.  An  oily,  light  yellow  liquid, 
sp.  gr.  1.653;  has  been  distilled  at  71°;  but  when  heated  to  96°,  when 
subjected  to  concussion,  or  when  brought  in  contact  with  phosphorus, 
spirits  turpentine,  alkalies,  oils,  or  grease,  etc.,  it  is  decomposed  into  one 
volume  of  nitrogen  and  three  volumes  of  chlorine,  the  decomposition 
being  attended  with  a  violent  explosion.  Owing  to  the  force  which  this 
explosion  exerts,  great  care  should  be  had  that  the  conditions  for  the  for- 
mation of  nitrogen  chloride  should  not  be  fulfilled.  If  by  accident  the 
substance  be  formed,  the  laboratory  should  be  closed  and  abandoned  for 
a  few  days,  during  which  the  chloride  will  suffer  spontaneous  decompo- 
sition. 

Nitrogen  bromide — NBr3 — has  been  obtained  as  a  reddish  brown, 
syrupy  liquid,  very  volatile,  and  resembling  the  chloride  in  its  properties, 
by  the  action  of  potassium  bromide  upon  nitrogen  chloride. 

Nitrogen  iodide,  NI3. — When  iodine  is  brought  in  contact  with  ammo- 
nium hydrate  solution,  a  dark  brown  or  black  powder,  highly  explosive 
when  dried,  is  formed.  This  substance  varies  in  composition  according 
to  the  conditions  under  which  the  action  occurs;  sometimes  the  iodide 
alone  is  formed;  under  other  circumstances  it  is  mixed  with  compounds 
containing  nitrogen,  iodine,  and  hydrogen. 


PHOSPHORUS. 
P 31 

Discovered  in  1669,  by  Brandt,  of  Hamburg,  while  searching  for  the 
philosopher's  stone  in  urine.  Brandt,  however,  kept  his  process  a  secret, 
and  the  discovery  was  subsequently  repeated  by  Kunckel  and  by  Boyle. 
In  1769,  Gahn  detected  its  existence  in  bones,  and  Scheele  suggested  a 
process  for  obtaining  it  from  this  source.  It  does  not  exist  in  nature  in 
its  elementary  form,  but  exclusively  in  phosphates  and  in  certain  organic 
substances. 

Phosphorus  is  obtained  from  bone-ash,  in  which  it  exists  as  tricalcic 
phosphate  (q.  -y.);  this,  by  treatment  with  sulphuric  acid,  is  converted 
into  the  soluble  monocalcic  phosphate — 

(PO4)aCa3  +  2S04H2=:  (P04)aCaH4+2S04Ca, 

which  is  separated  by  solution,  decantation,  and  evaporation,  from  the  calcic 
sulphate.  The  phosphate  is  then  mixed  with  about  one-fourth  its  weight 
of  powdered  charcoal  and  sand,  and  dried  to  such  an  extent  that  about  five 


PHOSPHORUS.  107 

per  cent,  of  water  is  retained.  The  dried  mixture  is  introduced  into  clay 
retorts,  whose  beaks  dip  under  water  contained  in  a  suitable  receiver;  the 
retorts  are  heated,  to  redness  at  first,  and  finally  to  a  white  heat.  Dur- 
ing the  first  portion  of  the  heating,  the  monocalcic  phosphate  is  converted, 
by  loss  of  water,  into  the  metaphosphate — 

(P04)2CaH4=  (P08)2Ca+2HaO, 

and  this  is  in  turn  reduced  by  the  charcoal,  while  the  silicon  dioxide  re- 
moves the  calcium  as  silicate: 

2(PO,)aCa-r-2SiOa-f  5C,=2Si  O3Ca+10CO  +  P4. 

The  crude  product  so  obtained  is  purified  either  by  redistillation,  or  by 
fusing  it  under  warm  water,  and  oxidizing  the  impurities  with  a  small 
quantity  of  sulphuric  acid  and  potassium  dichromate.  Finally,  the  phos- 
phorus is  cast  into  glass  moulds,  under  water. 

Phosphorus  exists  in  two  distinct  allotropic  conditions,  which  differ 
from  each  other  materially  in  their  physical  properties,  as  well  as  in  the 
activity  of  their  chemical  actions. 

The  ordinary  variety,  also  known  as  white,  and  formerly  as  crystalliz- 
able  phosphorus,  is  that  obtained  by  the  process  described  above.  It  is 
a  colorless  or  yellowish,  translucid  solid,  of  about  the  consistency  of  wax. 
Below  0°  it  is  brittle  ;  it  melts  at  44°.3,  and  boils  at  290°  in  an  atmos- 
phere not  capable  of  acting  upon  it  chemically,  being  converted  into  a 
colorless  gas  whose  specific  gravity  is  4.3A — 61.1  H.  It  gives  off  vapors 
at  temperatures  below  its  boiling-point,  and  when  water  is  boiled  upon 
it  the  aqueous  vapors  are  charged  with  its  vapor.  The  specific  gravity  of 
the  solid  is  1.83  at  10°.  When  exposed  to  the  air  it  gives  off  white 
fumes,  and  the  odor  of  ozone  is  observed.  In  the  dark  it  produces  a 
peculiar  pale  light,  and  to  this  property  it  owes  its  name  of  "  light 
bearer"  (<£<os-<£€Jo<o).  It  is  insoluble  in  water  and  in  alcohol,  soluble  in 
carbon  disulphide,  benzine,  petroleum,  ether,  and  in  the  fixed  and  essen- 
tial oils.  Its  solutions  on  evaporation  leave  it  in  the  form  of  octahedral 
or  dodecahedral  crystals,  in  which  latter  form  it  may  also  be  obtained  by 
the  solidification  of  fused  phosphorus. 

The  red  variety  is  obtained  from  the  white  by  maintaining  the  latter 
at  a  temperature  of  about  250°,  for  thirty-six  hours  or  more,  in  an  atmos- 
phere of  carbon  dioxide,  and  washing  the  residue  with  carbon  disulphide 
as  long  as  anything  is  dissolved. 

It  is  an  odorless,  tasteless  solid,  which  does  not  fume  when  exposed 
to  the  air,  and  is  not  soluble  in  the  solvents  of  the  ordinary  variety.  Its 
color  and  density  depend  upon  the  temperature  at  which  it  was  formed  ; 
it  is  usually  brownish  red,  and  of  sp.  gr.  2.1.  When  heated  to  the 
temperature  of  its  formation  it  does  not  melt,  but  at  a  slightly  higher 
temperature  is  converted  into  the  white  variety,  which  either  ignites  or 
distils  according  to  the  conditions  under  which  the  conversion  occurs. 
The  red  variety  may  also  be  obtained  in  the  crystalline  form,  but  not  as 
readily  as  white  phosphorus. 

Besides  these  two  forms,  there  are  others  which  are  by  some  authors 
considered  as  distinct  allotropic  varieties.  One  of  these  is  formed  as  a 
white  crust,  when  the  ordinary  phosphorus  is  exposed,  under  water 
holding  air  in  solution,  to  diffuse  daylight.  Another  form,  called  black 
phosphorus,  is  produced  when  ordinary  phosphorus,  which  has  been 
repeatedly  distilled,  is  heated  to  70°  and  cooled  suddenly. 


108  GENERAL    MEDICAL    CHEMISTRY. 

One  of  the  most  prominent  properties  of  phosphorus  is  the  readiness 
with  which  it  unites  with  oxygen.  If  ordinary  phosphorus  be  heated  in 
contact  with  air  to  60°,  or  if  it  be  exposed  in  a  finely  divided  state  to  air  at 
the  ordinary  temperature,  it  ignites  and  burns  with  a  bright  flame,  giving 
off  dense,  white  clouds  of  phpsnhorus  pentoxide  ;  it  may  even  be  burned 
under  water  heated  above  its  fusing-p$fnt,  by  causing  a  current  of  oxy- 
gen to  come  in  contact  with  it.  The  readiness  with  which  white  phosphorus 
fires,  and  the  serious  nature  of  the  burns  caused  by  it  (see  below),  render 
the  greatest  caution  necessary  in  handling  it  ;  it  must  always  be  kept 
under  water  (it  is  best  to  use  boiled  water  and  to  kee*p  the  bottle  in  the 
dark)  ;  it  should  never  be  brought  in  contact  with  the  skin  except  under 
water,  and  wrhen  it  is  to  be  cut,  this  should  be  done  under  water.  If 
desired  in  a  finely  divided  condition,  it  may  be  fused  in  warm  water 
(water  holding  urea  in  solution  is  better  than  pure  water)  and  shaken 
until  it  has  solidified  by  the  cooling  of  the  water. 

The  red  variety  does  not  unite  with  oxygen  so  readily,  and  may  be 
kept  exposed  to  the  air  and  handled  with  impunity.  When  exposed  to 
damp  air  it  oxidizes  slowly,  but  does  not  become  luminous  in  the  dark. 

Either  variety  unites  readily  with  chlorine,  bromine,  and  iodine,  with 
formation  of  chlorides,  bromides  and  iodides  (<^.  v.)  The  union  of  these 
elements  with  the  white  variety  is  attended  with  the  liberation  of  heat 
and  of  light.  Most  other  elements  are  capable  of  uniting  directly  with 
phosphorus;  hydrogen,  nitrogen  and  carbon  are  not.  Many  salts  are  re- 
duced by  white  phosphorus.  When  immersed  in  a  solution  of  cupric  sul- 
phate the  surfaces  of  a  fragment  of  phosphorus  became  coated  with 
metallic  copper;  in  a  solution  of  silver  nitrate  the  surface  of  the  phos- 
phorus becomes  blackened  by  the  deposition  upon  it  of  the  black  silver 
phosphide. 

Action  on  the  Economy. 

The  two  varieties  of  phosphorus  differ  from  each  other  in  the  impor- 
tant particular  that,  wThile  the  red  phosphorus  is  practically  inert  when 
taken  internally — probably  owing  to  its  insolubility — and  is  but  little 
liable  to  give  rise  to  burns,  the  white  variety  is  actively  poisonous,  and, 
when  ignited  in  contact  with  the  skin,  produces  very  painful  wounds, 
whose  effects  are  serious  beyond  what  could  be  expected  from  the  mere 
local  injury  produced.  A  burning  fragment  of  white  phosphorus  adheres 
tenaciously  to  the  skin,  into  which  it  burrows  in  burning.  One  of  the 
products  of  the  combustion  is  metaphosphoric  acid,  which,  being  absorbed, 
gives  rise  to  true  poisoning  (see  p.  115).  Cases  are  not  wanting  in  which 
death  has  followed  burns  by  phosphorus,  of  an  extent  which  would  not 
be  serious  if  caused  by  the  combustion  of  other  substances.  Burns  by 
phosphorus  should  be  washed  immediately  with  dilute  Javelle  water,  liq. 
sod.  chlorinatse,  or  solution  of  chloride  of  lime. 

When  taken  internall\T,  phosphorus  (the  ordinary  variety)  is  one  of 
the  most  insidious  of  poisons,  and  one  which,  on  the  continent  of  Europe, 
has  of  late  years  become  the  favorite  agent  in  homicidal  poisoning — the 
average  number  per  annum  of  cases  of  criminal  poisoning  by  phosphorus 
in  Paris  being  greater  than  that  of  cases  of  the  same  nature,  in  which 
arsenic  was  used.  Whether.such  cases  are  of  frequent  or  rare  occurrence 
in  the  United  States,  it  is  difficult  to  determine,  from  the  meagre  and  un- 
reliable statistics  at  hand.  Certain  it  is  that  the  number  of  accidental  and 
suicidal  deaths  from  phosphorus  and  "  rat-poison,"  noted  in  the  reports 


ACTION    ON    THE    ECONOMY.  109 

of  the  New  York  Board  of  Health  for  the  past  ten  years,  would  indicate 
that  the  toxic  nature  of  these  substances  is  not  unknown  among  our  popu- 
lation. 

The  substances  generally  used  are  match-heads,  or  "rat's  bane" — the 
former  being  in  the  ordinary  sulphur  match,  a  mixture  of  potassium 
chloride,  very  fine  sand,  phosphorus,  and  a  coloring  matter,  Prussian  blue 
or  vermilion  ;  and  the  latter  a  paste  of  flour  charged  with  phosphorus. 
It  is  not  improbable  that  the  recently  introduced  medicinal  preparations 
of  phosphorus  may  produce  fatal  poisoning  in  the  future.  The  symptoms 
in  acute  phosphorus-poisoning  appear  with  greater  or  less  rapidity,  ac- 
cording to  the  dose,  and  the  presence  or  absence  in  the  stomach  of  sub- 
stances which  favor  its  absorption.  Their  appearance  may  be  delayed 
for  days,  but  as  a  rule  they  appear  within  a  few  hours.  A  disagreeable, 
garlicky  taste  in  the  mouth,  and  heat  in  the  stomach  are  first  observed,  the 
latter  gradually  developing  into  a  burning  pain,  accompanied  by  vomiting 
of  dark-colored  matter,  which,  when  shaken  in  the  dark,  is  phosphores- 
cent ;  low  temperature,  and  dilatation  of  the  pupils.  In  some  cases  death 
follows  at  this  point  suddenly,  without  the  appearance  of  any  further 
marked  symptoms  ;  usually,  however,  the  patient  rallies,  seems  to  be 
doing  well,  until  suddenly  jaundice  makes  its  appearance,  accompanied 
by  retention  of  urine,  and  frequently  delirium,  followed  by  coma  and 
death. 

There  is  no  known  chemical  antidote  to  phosphorus  ;  the  treatment 
is,  therefor,  limited  to  the  removal  of  the  unabsorbed  portions  of  the 
poison  by  the  action  of  an  emetic,  zinc  sulphate  or  apomorphia,  as  expe- 
ditiously  as  possible,  and  the  administration  of  oil  of  turpentine — the 
older  the  oil  the  better — as  a  physiological  antidote.  The  use  of  fixed 
oils  or  fats  is  to  be  avoided,  as  they  favor  the  absorption  of  the  poison 
by  their  solvent  action.  The  prognosis  is  very  unfavorable. 

As  commercial  phosphorus  is  usually  contaminated  with  arsenic,  the 
effects  of  the  latter  substance  may  also  appear  in  poisoning  by  the  former. 

Analysis. — When,  after  a  death  supposed  to  be  caused  by  phos- 
phorus, chemical  evidence  of  the  existence  of  the  poison  in  the  body,  etc., 
is  desired,  the  investigation  must  be  made  as  soon  after  death  as  possi- 
ble, for  the  reason  that  the  element  is  rapidly  oxidized,  and  the  detection  of 
the  higher  stages  of  oxidation  of  phosphorus  is  of  no  value  as  evidence  of 
the  administration  of  the  element,  because  they  are  normal  constituents 
of  the  body  and  of  the  food. 

The  detection  of  elementary  phosphorus  in  a  systematic  toxicological 
analysis  is  connected  with  that  of  prussic  acid,  alcohol,  ether,  chloroform, 
and  other  volatile  poisons.  The  method  adopted  should  be  a  combination 
of  the  processes  of  Mitscherlich,  Blondlot,  and  Neubauer  and  Frezenius. 
Mitscherlich's  process  would  be  sufficient  of  itself  were  it  not  that  the 
power  of  phosphorescence  of  phosphorus  is  held  in  abeyance  by  the 
presence  of  alcohol  or  ether,  and  is  permanently  destroyed  by  admixture 
of  oil  of  turpentine,  the  last-named  substance  being  one  which  is  very 
liable  to  be  mixed  with  the  contents  of  the  stomach,  if  the  case  have  been 
recognized  as  one  of  phosphorus-poisoning  before  death. 

The  substances  to  be  examined,  usually  the  contents  of  the  stomach 
(the  other  volatile  poisons  should  be  looked  for  first  in  the  lungs),  are 
diluted  with  water,  acidulated  with  sulphuric  acid,  and  heated  in  a  flask 
over  the  sand-bath.  The  flask  is  connected  by  a  perforated  cork  and  a 
long,  bent  tube,  with  a  Liebig's  condenser  placed  in  a  vertical  position  and 
in  absolute  darkness,  and  so  arranged  as  to  deliver  the  distillate  into  a 


110  GENERAL   MEDICAL    CHEMISTRY. 

suitable  receiver,  while  through  the  entire  apparatus  a  current  of  carbon 
dioxide  is  made  to  pass.  The  odor  of  the  distillate  is  noted.  If  phos- 
phorus be  present,  it  is  usually  garlicky.  The  condenser  is  also  observed. 
If  at  the  point  of  greatest  condensation  a  faint,  luminous  ring  be  observed 
(in  the  absence  of  all  reflections),  it  is.  proof  positive  of  the  presence  of 
unoxidized  phosphorus;  the  absence,>nowever,  of  that  poison  is  not  to  be 
inferred  from  the  absence  of  the  luminous  ring.  If  this  fail  to  appear 
when  one-third  the  fluid  contents  of  the  flask  have  passed  over,  the  re- 
ceiver is  removed  (its  contents  being  reserved  for  the  detection  of  the 
more  volatile  poisons),  and  in  its  place  are  arranged  two  V-tubes,  or  a 
Liebig's  bulb-tube  filled  with  neutral  solution  of  silver  nitrate.  If  phos- 
phorus be  present,  either  in  its  own  form  or  in  its  lower  stages  of  oxida- 
tion, a  black  deposit  of  silver  phosphide  is  formed;  if  no  blackening 
of  the  silver  solution  occur,  the  absence  of  phosphorus  may  be  inferred. 
If  blackening  have  occurred,  the  deposit  is  introduced  into  the  generator 
of  an  apparatus  furnishing  pure  hydrogen  (see  Zinc),  which,  after  drying 
over  sulphuric  acid,  is  burned  as  it  issues  from  a  platinum  jet.  If  the  black 
deposit  be  silver  phosphide,  the  inner  portion  of  the  flame  will  be  bright 
green,  and  will  exhibit  the  characteristic  green  lines  of  phosphorus  when 
examined  spectroscopically. 

Chronic  poison  ing  by  phosphorus. — This  form  of  poisoning,  also  known 
as  the  Lucifer  disease,  occurs  among  operatives  engaged  in  the  dipping, 
drying,  and  packing  of  phosphorus  matches.  Sickly  women  and  children 
are  most  subject  to  it.  Workmen  in  factories  where  the  element  itself 
is  produced  are  not  affected.  The  cause  of  the  disorder  is  variously 
ascribed  to  the  contamination  of  phosphorus  with  arsenic,  and  to  the 
presence  in  the  atmosphere  of  oxides  of  phosphorus  and  ozone.  The  prog- 
ress of  the  disease  is  slow,  and  its  most  prominent  and  culminating  mani- 
festation is  the  destruction  of  one  or  both  maxillae  by  necrosis. 

The  frequency  of  the  disease  may  be  in  some  degree  diminished  by 
maintaining  a  thorough  ventilation  of  the  shops,  by  frequently  washing 
the  face  and  rinsing  the  mouth  with  a  weak  solution  of  sodium  carbonate, 
and  by  exposing  oil  of  turpentine  in  saucers  in  the  workshops.  By  none 
of  these  methods,  however,  will  the  prevention  of  the  disease  be  perfect — 
a  result  which  can  only  be  attained  by  abandoning  the  use  of  white 
phosphorus,  for  the  manufacture  of  matches,  entirely.  The  increased 
cost  of  red  phosphorus  is  of  no  weight  against  the  advantages  of  prevent- 
ing this  fearful  disease,  and  at  the  same  time  removing  from  the  reach 
of  the  poisoner  one  of  the  most  potent  and  easily  obtained  of  toxic  agents. 


Hydrogen  Phosphides. 

There  exist  no  less  than  three  compounds  of  hydrogen  and  phospho- 
rus, of  which  the  most  important  is  the  one  corresponding  in  composi- 
tion to  ammonia. 

Gaseous  •  hydrogen  phosphide — Phosphonia — Phosphamine — PH3 — a 
gaseous  substance,  two  volumes  of  which  contain  half  a  volume  of  vapor 
of  phosphorus  and  three  volumes  of  hydrogen. 

It  is  formed  in  a  number  of  reactions,  but  can  only  be  obtained  in  a 
state  of  purity  by  the  decomposition  of  phosphonium  iodide,  PH4I,  by 
water,  or  by  solutions  of  the  alkalies.  As  thus  obtained,  it  is  a  colorless 
gas,  having  a  strong  alliaceous  odor,  very  sparingly  soluble  in  water  ; 


OXIDES    OF    PHOSPHORUS.  Ill 

sp.  gr.  1.134A — 17.5H.  It  fires  at  about  70°,  or  on  contact  with  fum- 
ing nitric  acid,  chlorine,  bromine,  or  iodine. 

The  methods  usually  employed  for  obtaining  the  gas  are,  by  heating 
phosphorus  with  a  strong  solution  of  potassium  hydrate,  or  with  thick 
milk  of  lime  ;  or  by  decomposing  calcium  phosphide  by  water.  When 
prepared  by  these  methods  the  gas  differs  from  the  pure  substance,  in 
that  as  each  bubble  comes  in  contact  with  air  it  takes  fire  spontaneously, 
with  the  formation  of  a  white  ring  of  phosphorus  pentoxide;  this  property 
it  owes  to  the  presence  of  traces  of  another  compound  (see  below). 

The  impure  gas  is  also  formed  during  the  putrefaction  of  organic  sub- 
stances containing  phosphorus.  The  natural  phenomenon  of  ignis  fatuus, 
or  Will  o'  the  Wisp,  is  probably  due  to  such  a  formation  of  hydrogen 
phosphide. 

The  gas  is  highly  poisonous,  even  when  the  air  contains  less  than  one 
per  cent.  Its  poisonous  action  is  due  to  its  oxidation  at  the  expense  of 
the  blood-coloring  matter,  whose  destruction  produces  death  by  asphyxia. 
After  de*ath  the  blood  is  found  to  be  dark,  to  have  a  violet  tinge,  and  to 
have,  in  a  great  measure,  lost  its  capacity  for  absorbing  oxygen. 

Liquid  hydrogen  phosphide — P2H4 — is  the  substance  whose  vapor 
communicates  to  PH3  its  property  of  spontaneously  igniting  on  contact 
with  air.  It  may  be  obtained  by  passing  the  gas,  obtained  by  the  decom- 
position of  calcium  phosphide  by  water,  through  a  bulb-tube  enclosed  in 
a  freezing  mixture. 

It  is  a  colorless,  heavy  liquid,  readily  decomposable  at  a  temperature 
of  30°,  and  by  other  influences  which  also  destroy  the  spontaneous  in- 
flammability of  the  gaseous  product. 

Solid  hydrogen  phosphide — P4H2. — A  yellow  solid,  formed  by  the  de- 
composition of  PaH4,  under  the  influence* of  sunlight.  It  is  not  phos- 
phorescent, and  only  ignites  when  heated  to  160°. 


Oxides  of  Phosphorus. 

These  are  two  in  number: 


Phosphorus  trioxide 
Phosphorus  pentoxide 


Phosphorus  trioxide  —  Phosphorus  anhydride  —  P2O3  —  is  formed,  as  a 
white  solid,  when  phosphorus  is  burned  in  a  limited  supply  of  dry  air  or 
oxygen.  When  exposed  to  moist  air  it  is  fired  by  the  heat  developed  by 
its  union  with  water  to  form  phosphorous  acid. 

Phosphorus  pentoxide  —  Phosphoric  anhydride  —  P2O5—  is  formed 
whenever  phosphorus  is  caused  to  burn,  in  the  absence  of  water,  and  in 
the  presence  of  an  excess  of  oxygen.  It  is  a  white,  flocculent  solid,  which 
exhibits  almost  as  great  a  tendency  to  unite  with  water  as  does  the  lower 
stage  of  oxidation. 

When  exposed  to  the  air  it  absorbs  moisture  rapidly,  with  liberation 
of  heat  and  formation  of  a  highly  acid  liquid,  which  does  not  contain  or- 
thophosphoric  acid,  as  we  should  expect  from  analogy,  but  metaphosphoric 
acid  (q.  v.).  It  is  frequently  used  in  the  laboratory  as  a  very  energetic 
drying  agent. 


112  GENERAL    MEDICAL    CHEMISTRY. 


Phosphorus  Acids. 

These  form  a  series  of  great  interest  from  a  theoretical  point  of  view. 
The  first  has  no  corresponding  oxide;  the  second  is  the  hydrate  of  the  tri- 
oxide,  and  the  other  hydrates'  are  refjefrable,  directly  or  indirectly,  to  the 
pentoxide: 

Hypophosphorous  acid PO2H3. 

Phosphorous  acid .*-.  .PO3H3. 

Orthophosphoric  acid. PO4H3. 

Pyrophosphoric  acid P2O7H4. 

Metaphosphoric  acid POSH. 

The  basicity  of  these  acids  is  also  of  interest.  While  PO3H  is  mono- 
basic, and  PaO7H4  is  tetrabasic,  all  of  their  hydrogen  atoms  being  replace- 
able— the  other  three,  although  each  containing  three  atoms  of  hydrogen, 
vary  in  basicity:  POaHg  is  monobasic;  PO3H3,  dibasic;  and  PO4H3,  tribasic. 


Hypophosphorous  Acid — PO3H3, 

Is  obtained  as  a  strongly  acid,  colorless,  syrupy  liquid,  by  decomposing 
its  barium  salt  with  an  equivalent  quantity  of  sulphuric  acid,  filtering 
and  concentrating'  the  solution.  It  may  also,  with  proper  precautions, 
be  obtained  in  the  crystalline  form.  It  is  quite  unstable,  and,  when  ex- 
posed to  the  air,  is  oxidized  into  a  mixture  of  phosphorous  and  phosphoric 
acids.  Its  salts  are  more  stable,  and  some  are  used  in  medicine;  they  have 
the  composition  PO8H8M'  or  (PO2H2)2M". 


Phosphorous  Acid— PO8H8, 

Is  best   prepared    by  the   decomposition   of    phosphorus    trichloride    by 
water,  according  to  tl.e  equation: 

PC13  +  3H2O  =  PO3II3 

The  hydrochloric  acid  formed  is  driven  off  by  evaporation  and  by  ex- 
posure over  quicklime.  The  product  is  finally  concentrated  over  sulphuri* 
acid.  It  is  also  formed  by  exploding  a  mixture  of  phosphonia  and  oxygen, 
in  the  proportion  of  two  volumes  of  the  former  to  three  volumes  of  the 
latter.  It  is  a  syrupy  and  highly  acid  liquid,  readily  decomposable  by 
heat.  It  is  an  energetic  reducing  agent,  taking  up  oxygen  to  form 
phosphoric  acid.  It  forms  salts  called  phosphites,  whose  composition  is 
PO.HM1I,  PO3HM'2,  or  PO.HM". 

It  has  been  stated  that  this  acid  is  formed  in  concentrated  aqueous 
solution,  when  phosphorus  is  exposed  to  the  slow  action  of  moist  air;  bu1 
from  the  recent  researches  of  P.  Salzer  it  would  seem  that  the  solutioi 
so  obtained  contains  a  new  acid,  which  he  calls  hypophosphoric  acid,  an< 
to  which  he  ascribes  the  formula  PO8H2(?). 


PYROPHOSPHORIC    ACID.  113 


Orthophosphoric  Acid. 

Common,  or  tribasic  phosphoric  acid,  PO4H3. — This  acid,  although 
not  existing  free,  is  widely  disseminated  in  the  three  kingdoms  of  nature 
in  its  salts,  the  phosphates. 

It  is  usually  obtained  by  the  oxidation  of  phosphorus  by  dilute  nitric 
acid,  under  the  influence  of  heat.  The  action  is  liable  to  become  violent, 
and  the  process  should  always  be  conducted  with  caution;  indeed,  it  is 
best  to  use  the  red  phosphorus  in  place  of  the  ordinary  variety.  This  is 
the  process  adopted  (with  subsequent  dilution)  in  the  United  States  and 
British  Pharmacopoeias,  to  obtain  the  Acid,  phosph.  dilutum  (see  Meta- 
phosphoric  Acid),  enough  nitric  acid  being  used  to  oxidize  the  phos- 
phorus completely,  and  the  excess  being  driven  off  by  heat.  The  strength 
of  the  United  States  preparation  is  10.21  per  cent.,  PO4H3;  sp.  gr., 
1,056;  that  of  the  British  14.42  per  cent.,  PO4H3;  sp.  gr.,  1.08. 

In  the  arts  phosphoric  acid  is  now  usually  obtained  directly  from  bone 
ash,  by  converting  the  calcium  phosphate  contained  in  them  into  lead 
or  barium  phosphate;  the  insoluble  compound  is  removed  and  decom- 
posed by  hydrogen  sulphide  in  the  first  case,  and  by  sulphuric  acid  in 
proper  proportion  in  the  second. 

It  is  also  formed  in  other  reactions,  as  by  passing  chlorine  into  phos- 
phorus melted  under  water,  when  phosphorus  pentachloride  is  formed 
and  immediately  decomposed  into  phosphoric  and  hydrochloric  acids;  the 
latter  is  removed  by  evaporation. 

The  concentrated  acid  usually  is  a  colorless,  transparent,  syrupy  fluid, 
which  still  contains  water,  and,  by  exposure  over  sulphuric  acid,  yields 
the  pure  acid  in  the  form  of  transparent,  prismatic  crystals,  which,  on 
exposure  to  air,  rapidly  deliquesce,  forming  a  highly  acid,  syrupy  solution. 

For  the  action  of  heat  on  this  acid,  see  below  ;  for  tests  (see  p.  114). 
It  forms  many  salts,  whose  composition  is:  PO4H2M';  PO.HM'  ;  PO.M'  ; 
(P04)2M"3;  (P04H)2M"2;  (PO4H2)2M";  or  PO4M'M". 

Phosphoric  acid  made  from  arsenical  phosphorus  (commercial  phos- 
phorus is  usually  arsenical),  is  contaminated  with  arsenic  trioxide,  whose 
presence  may  be  recognized  by  the  application  of  Marsh's  test  (p.  129) 
to  the  aqueous  solution.  The  aqueous  acid  should,  on  evaporation,  leave 
no  residue  ;  and  should  not  respond  to  the  indigo  or  ferrous  sulphate 
tests  for  nitric  acid. 


Pyrophosphoric  Acid — P3O7H4. 

When  orthophosphoric  acid  (hydrodisodic  phosphate)  is  maintained 
for  some  time  at  a  temperature  of  213°,  two  of  its  molecules  unite, 
with  loss  of  the  elements  of  one  molecule  of  water,  to  form  a  new  acid — 
pyrophosphoric  acid,  so  called  from  its  igneous  origin: 

2P04H3=P207H4+H20. 

The  acid  is  obtained  free  as  a  transparent,  vitreous,  semi-crystalline, 
soft  mass,  by  decomposing  its  lead  salt  with  hydrogen  sulphide,  filtering 
and  concentrating  the  filtrate.  It  is  tetrabasic. 


GENERAL    MEDICAL    CHEMISTRY. 


Metaphosphoric  Acid. 

Glacial  phosphoric  acid,  PO3H. — This  acid,  whose  composition  is 
similar  to  that  of  nitric  acid,  .is  formed  by  the  action  of  heat,  approaching 
redness,  on  either  ortho-  or  pyrophospbroric  acid.  In  either  case  there  is 
loss  of  the  elements  of  a  molecule  of  water  : 

PO4H3-H2O=PO3H. 
P9O7H4  -  H2O = 2PO8H. 

It  is  usually  obtained  directly  from  bone-ash,  whose  calcium  phos- 
phate is  first  converted  into  ammonium  phosphate,  which  is  then  sub- 
jected to  a  red  heat.  This  is  the  process  adopted  by  the  United  States 
Pharmacopeia  in  obtaining  the  Acid,  phosphor icum  glaciale  (see  p.  115). 

It  appears  as  a  white,  glassy,  transparent  solid,  odorless,  and  having 
a  sour  taste.  Slowly  deliquescent  when  exposed  to  the  air,  it  is  very 
soluble  in  water,  the  solution  taking  place  quite  slowly,  and  being  ac- 
companied by  a  peculiar  crackling  sound  at  intervals. 


Analytical  Characters  of  the  Phosphoric  Acids. 

The  three  acids,  PO4H3,  P2O,H2,  and  PO3H,  although  closely  related 
and  all  derived  from  the  oxide  PaO5,  differ  materially  in  their  properties, 
and  may,  in  solution  of  the  free  acids  or  of  their  salts,  be  distinguished 
from  each  other  by  the  following  reactions  : 

Orthophosphoric  acid.  Pyrophosphoric  acid.  Metaphosphoric  acid. 

With  Ammontacal  Solution  of  Silver  Nitrate. 
A  yellow  precipitate.  A  white  precipitate.  A  white  precipitate. 

With  Solution  of  Albumen. 
No  effect.  No  effect.  Coagulation. 

With  Solution  of  Ammonium  Molybdate  in  Nitric  Acid. 
A  yellow  precipitate.  No  effect.  No  effect. 

With  Solution  of  Magnesium  Sulpliate  in  the  Presence  of  Ammonium  Chloride  and 

Hydrate. 

A  white,  crystalline  precipi-  A  white  precipitate  ;  sola-    No  effect ;   or   a   precipitate 

tate;  insoluble  in  ammo-  ble    in  excess  of  phos-        soluble  in  ammonium  chlo- 

nium  hydrate,  nearly  so  phate  or  of  magnesium        ride, 

in  ammonium  chloride  ;  sulphate, 
soluble  in  acids. 

The  last  two  reactions  are  only  of  value  in  the  absence  of  arsenic  acid. 

The  quantitative  determination  of  phosphoric  acid  is  always  a  tedious 
and  delicate  operation,  and  a  discussion  of  the  various  methods  proposed 
would  fill  a  volume.  With  the  simple  statement  that  the  acid  is  finally 
weighed  as  uranium  or  magnesium  phosphate,  the  reader  is  referred  to 
the  works  on  analytical  chemistry. 


COMPOUNDS    OF   PHOSPHORUS   AND    SULPHUR.  115 


Action  on  the  Economy. 

Although  the  salts  of  orthophosphoric  acid  are  important  constituents 
of  animal  tissues,  and  give  rise,  when  taken  internally  in  reasonable  doses, 
to  no  untoward  symptoms;  and  although  the  acid  itself,  when  ingested, 
may  act  deleteriously  purely  by  virtue  of  its  acid  reaction,  the  recent  re- 
searches of  Gamgee,  Priestley,  and  Larmuth,  have  shown  that  meta-  and 
pyrophosphoric  acids,  even  when  taken  in  the  form  of  neutral  salts,  have 
a,  distinct  action  (the  pyro  being  the  more  active)  upon  the  motor  ganglia 
of  the  heart,  producing  diminution  of  the  blood-pressure,  and,  in  compara- 
tively small  doses,  death  from  cessation  of  the  heart's  action.  The  dis- 
tinction between  the  glacial  and  dilute  acids  of  the  United  States  Phar- 
inacopoaia  becomes  of  importance  in  view  of  these  facts. 


Compounds  of  Phosphorus  with  Elements  of  the  Chlorine  Group. 

The  compounds  of  phosphorus  and  chlorine  are  three  in  number: 
PC13,  PC16,  and  POC13. 

Phosphorus  trichloride — PC13 — is  prepared  by  passing  vapor  of  phos- 
phorus over  mercuric  chloride;  or,  preferably,  by  passing  a  slow  current 
of  dry  chlorine  over  phosphorus,  and  purifying  by  distillation. 

It  is  a  colorless  liquid;  sp.  gr.  1.61;  has  an  irritating  odor;  fumes  in 
the  air;  boils  at  76°.  On  contact  with  water  it  is  decomposed,  with  for- 
mation of  phosphorous  and  hydrochloric  acids.  It  is  a  very  valuable 
reagent  in  organic  chemistry. 

Phosphorus  pentachloride — PC1& — is  formed  by  the  action  of  an  ex- 
cess of  chlorine  upon  phosphorus,  or  upon  the  trichloride. 

It  occurs  in  light  yellow  crystals,  having  a  powerful  odor,  giving  off 
irritating  vapors,  and  distilling  at  about  145°.  At  higher  temperatures 
it  is  decomposed  into  PC13  +  C12.  With  a  small  quantity  of  water  it 
forms  the  oxychloride,  POC13,  and  hydrochloric  acid;  with  a  large  quan- 
tity, phosphoric  and  hydrochloric  acids.  Is  useful  as  a  reagent  in  organic 
chemistry. 

Phosphorus  oxychloride — POC13 — is  formed  by  the  action  of  a  limited 
quantity  of  water  on  the  pentachloride.  It  is  a  colorless  liquid;  sp.  gr. 
1.7;  boils  at  110°;  solidifies  at  — 10°;  and  has  a  pungent  odor.  Use;  the 
«ame  as  that  of  the  other  chlorides. 

With  bromine,  phosphorus  forms  compounds  similar  in  composition 
and  properties  to  the  chlorine  compounds. 

With  iodine,  it  forms  two  compounds,  PI2  and  PI3,  both  solid,  crystal- 
line bodies,  obtained  by  the  direct  union  of  their  elements,  and  both  de- 
composed, on  contact  with  water,  into  hydriodic  and  phosphorous  acids. 

T \\ofluorides  of  phosphorus,  PF8  and  PF6,  are  also  known — the  former 
liquid,  the  second  gaseous. 


Compounds  of  Phosphorus  and  Sulphur. 

No  less  than  six  compounds  of  these  elements  have  been  described, 
having  the  formulae  :  P4S,  P2S,  P4S3,  P2S3,  P2S6,  P2S12.  Two  of  these,  P2S9 
and  P2S5,  correspond  to  the  oxides.  Although  of  great  interest  in  con- 
nection with  theoretical  chemistry,  they  are  not  of  medical  interest. 


116  GENERAL   MEDICAL    CHEMISTRY. 

ARSENIC. 
Arsenicum As 75 

Compounds  of  arsenic;  notably  tbe  sulphides,  were  known  to  the  an- 
cients, and  the  element  itself  to  the  alchemists  as  early  as  the  fourth  cen- 
tury, when  Geber  makes  mention  of  it. 

Arsenic  occurs  in  nature  in  the  form  of  metallic  arsenides,  but  princi- 
pally as  the  sulphides,  orpiment  and  realgar,  and  in  arsenical  iron  pyrites, 
or  mispickel,  the  last-named  mineral  being  one  of  the  chief  sources  from 
which  it  and  its  compounds  are  industrially  obtained.  It  is  also  found  in 
the  elementary  form  in  small  quantities,  and  distributed  in  a  vast  number 
of  other  substances  in  quantities  which,  if  not  large,  are  sufficiently  so  to 
become  a  serious  inconvenience  to  the  toxicologist. 

It  is  obtained  for  use  in  the  arts,  either  by  calcining  mispickel  and 
condensing  the  volatilized  arsenic  in  iron  tubes,  or  by  heating  a  mixture 
of  arsenious  oxide  and  charcoal,  when  the  former  is  reduced  and  element- 
ary arsenic  distils  over. 

It  is  a  brittle,  light  steel-gray  solid,  having  a  metallic  lustre;  sp.  gr. 
5.75.  When  heated  under  the  ordinary  pressure,  and  without  contact 
with  air,  it  volatilizes  without  previous  fusion.  Under  strong  pressure  it 
liquefies  at  a  red  heat.  The  density  of  its  vapor  is  10. 2 A — 147.3H  at 
560°;  10.6 A — 153H  at  860°.  Its  vapor  is  yellowish,  and  has  the  odor  of 
garlic,  which  is  probably  developed  during  oxidation.  It  is  insoluble  in 
water  and  in  other  liquids  which  do  not  act  upon  it  chemically  (see  p.  125). 

When  heated  in  air,  arsenic  is  rapidly  oxidized  to  arsenic  trioxide, 
and  ignites  at  somewhat  below  a  red  heat.  In  oxygen  it  burns  with  a 
brilliant  white  light,  having  a  bluish  tinge.  In  dry  air  it  is  not  altered, 
but  when  exposed  to  damp  air  its  surface  rapidly  becomes  tarnished  by 
oxidation.  Its  oxidation  is  attended  by  the  development  of  an  alliace- 
ous odor.  In  water  it  is  slowly  oxidized,  a  portion  of  the  oxide  formed 
dissolving  in  the  water.  It  unites  readily  with  chlorine,  bromine,  iodine, 
sulphur,  and  most  of  the  metals.  With  hydrogen  it  only  combines  when 
that  element  is  in  the  nascent  state.  Sulphuric  acid,  when  warm  and 
concentrated,  is  decomposed  by  arsenic  with  formation  of  sulphur  di- 
oxide, arsenic  trioxide,  and  water.  Nitric  acid  is  readily  decomposed, 
giving  up  its  oxygen  to  the  formation  of  arsenic  acid. 

With  hydrochloric  acid,  aided  by  heat,  arsenic  trichloride  is  formed. 
Arsenic  is  oxidized  by  fusion  with  potassium  hydrate,  hydrogen  is  given 
off,  and  a  mixture  of  arsenite  and  arsenide  of  potassium  remains,  which, 
by  increase  of  temperature,  is  converted  into  arsenic  and  potassium 
arsenate,  the  former  of  which  volatilizes,  and  the  latter  remains. 

Arsenic  is  used  in  the  arts  to  some  extent  in  pyrotechny,  entering 
into  the  composition  of  the  Bengal  light  (which  should,  therefor,  only  be 
used  in  the  open  air),  in  the  manufacture  of  shot,  and  of  fly-poison,  and 
as  a  medicine  in  veterinary  practice.  It  is  poisonous  (see  p.  125). 

Compounds  of  Arsenic  -with  Hydrogen. 

Two  of  these  are  known,  one  gaseous,  the  other  solid. 

Hydrogen  arsenide,  arseniuretted  hydrogen,  arsenia,  arsenamine,  AsIIs 
— a  compound  whose  composition  is  similar  to  that  of  ammonia  and  the 
corresponding  phosphorus  compound,  and  one  which  is  of  great  practical 


COMPOUNDS    OF    AKSENIC    WITH    HYDROGEN.  117 

as  well  as  theoretical  interest.  It  does  not  exist  in  nature,  and  was  dis- 
covered by  Scheele. 

It  is  formed:  First. — By  the  action  of  water  upon  an  alloy,  obtained 
by  fusing  together  a  mixture  of  two  parts  of  natural  sulphide  of  anti- 
mony, two  parts  of  cream  of  tartar,  and  one  part  of  arsenic  trioxide. 

Second. — By  the  decomposition  of  the  arsenides  of  zinc  and  tin  (as 
well  as  of  other  arsenides)  by  dilute  hydrochloric  or  sulphuric  acid. 

'Third. — Whenever  a  reducible  compound  of  arsenic  is  in  the  pres- 
ence of  nascent  hydrogen: 

As203  +  6S04H2  +  6Zn = 6SO4Zn  +  3H2O  + 2  AsH3. 

This  reaction  is  utilized  in  Marsh's  test  (see  p.  129). 

Fourth. — By  the  action  of  water  upon  the  arsenides  of  the  alkaline 
metals: 

AsNa3 + 3H20 = 3NaHO  +  AsH3. 

Fifth. — By  the  combined  action  of  moisture,  air,  and  organic  matter 
upon  arsenical  pigments  (see  p.  125).  It  is  a  colorless  gas,  having  a 
strong  alliaceous  odor,  soluble  in  five  volumes  of  water  free  from  air. 
Condenses  to  a  mobile  fluid  at  — 40°,  does  not  solidify  at  — 110°;  sp.  gr. 
2. 695  A— 38.91 6H. 

It  is  not  liable  to  spontaneous  decomposition,  but,  in  contact  with  air 
or  oxygen,  and  moisture,  its  hydrogen  is  slowly  removed  by  oxidation, 
and  elementary  arsenic  is  deposited.  It  is  also  decomposed  into  its 
elements  by  the  passage  through  it  of  the  luminous  electric  discharge. 
A  mixture  of  dry  oxygen  and  hydrogen  arsenide  remains  such  under 
ordinary  circumstances,  but,  upon  heating  it,  it  explodes  with  formation 
of  arsenic  trioxide  and  water,  three  volumes  of  oxygen  oxidizing  two  of 
the  arsenical  gas: 

2  AsH3 + 3O2 = As2O3  +  3H3O. 

With  a  quantity  of  oxygen  less  than  that  indicated  in  the  equation, 
•elementary  arsenic  is  deposited. 

If  the  gas  be  ignited  as  it  issues  from  a  jet,  it  burns  with  a  greenish 
ilame,  from  which  rises  a  white  cloud  of  arsenic  trioxide  ;  if,  however,  the 
ilame  be  cooled  by  the  introduction  of  a  cold  body,  the  hydrogen  is  alone 
oxidized,  the  arsenic  being  deposited  on  the  cold  surface  in  its  elementary 
form.  If  the  gas  be  heated  to  redness  as  it  passes  through  a  glass  tube, 
it  is  decomposed  in  whole  or  in  part,  hydrogen  passing  on  and  the  arsenic 
being  deposited.  If  hydrogen  arsenide  be  caused  to  bubble  through  a 
solution  of  silver  nitrate,  that  salt  is  decomposed  ;  elementary  silver  sepa- 
rates as  a  black  powder,  and  the  solution  contains  arsenic  trioxide.  The 
last  three  reactions  are  utilized  in  Marsh's  test  (q.  v.). 

Chlorine  decomposes  the  gas  with  great  energy — the  action,  which  is 
attended  with  considerable  danger  to  the  operator,  being  accompanied  by 
an  explosion,  and  the  formation  of  hydrochloric  acid  and  arsenic  tri- 
chloride. Bromine  and  iodine  act  in  a  similar  manner,  but  less  violently. 

If  hydrogen  „ arsenide  be  passed  over  solid  potassium  hydrate,  it  is 
partially  decomposed,  the  potash  being  coated  with  a  blackish  deposit  of 
what  would  seem  to  be  elementary  arsenic. 

All   oxidizing  agents  decompose  the  gas  readily,  water  and  arsenic 


118  GENERAL    MEDICAL    CHEMISTRY. 

trioxide  being  formed  by  the  action  of  the  less  active  oxidants,  and  water 
and  arsenic  acid  by  that  of  the  more  active. 

The  alkaline  hydrates  absorb  the  gas,  hydrogen  is  given  off,  and 
potassium  arsenite  remains  in  solution.  Many  metallic  elements,  when 
heated  in  an  atmosphere  of  .hydrogen  arsenide,  decompose  it  with  forma- 
tion of  a  metallic  arsenide,  and  liberation  of  hydrogen. 

Although  hydrogen  arsenide  and  hydrogen  sulphide  decompose  each 
other  to  a  great  extent,  with  separation  of  arsenic  trisulphide,  the  re- 
searches of  Kubel,  Meyers,  and  Otto  have  shown  that  the  former  gas  is 
capable  of  existing,  to  some  extent  at  least,  in  the  presence  of  the  latter; 
a  fact  which  renders  it  necessary  to  use  the  greatest  caution,  in  obtaining 
hydrogen  sulphide  for  toxicological  purposes,  to  use  materials  free  from 
arsenic. 

Arseniuretted  hydrogen  is  exceeding  poisonous  (see  p.  125). 

Solid  hydrogen  arsenide. — The  probable  composition  of  this  body  is 
As2H.  It  is  a  red-brown  powder,  insoluble  in  water  and  in  alcohol.  The 
only  interest  attaching  to  it  is  in  connection  with  Marsh's  test,  in  which 
care  should  be  had  to  avoid  the  conditions  under  which  it  is  formed.  This 
may  be  done  by  carefully  preventing  the  presence  of  any  nitrate,  and  by 
moistening  the  zinc  with  a  dilute  solution  of  platinum  chloride,  which 
should  be  removed,  and  the  zinc  washed  with  pure  v/ater  before  the  appa- 
ratus is  mounted  (see  p.  129). 


Compounds  of  Arsenic  and  Oxygen. 

/ 

Only  two  of  these  are  known  with  certainty  :  they  are  the  trioxide, 
As2O3,  and  the  pentoxide,  As2O&,  corresponding  to  the  similar  phos- 
phorus compounds.  It  is  probable  that  the  gray  substance,  formed  by 
the  action  of  moist  air  and  of  water  upon  elementary  arsenic,  is  a  lower 
oxide  than  either  of  the  above,  possibly  As2O. 


Arsenic  Trioxide. 

Arsenious  anhydride — "White  arsenic — Arsenic — Arsenious  acid — Aci- 
dum  arseniosum  (U.  S.,  Br.) — As2O3. — This  substance  does  not  exist  in 
nature,  but  is  manufactured  in  large  quantities  industrially,  either  as  a  dis- 
tinct product,  by  roasting  mispickel,  or  as  an  incidental  product  in  working 
the  ores  of  cobalt  and  nickel.  In  either  case  the  vapors  are  conducted 
into  suitable  condensing-chambers,  where  the  solid  trioxide  is  deposited 
as  a  white,  crystalline  powder,  known  in  the  arts  &s  flour  of  arsenic.  From 
time  to  time  this  is  removed  (an  operation  attended  with  no  little  danger 
to  the  workman*  employed),  and  purified  by  a  second  sublimation.  It 
sometimes  occurs  in  this  last  process  that,  owing  to  the  presence  of  ele- 
mentary arsenic,  the  iron  pot  in  which  the  impure  white  arsenic  is  heated 
is  perforated,  and  the  contents,  flowing  into  the  fire,  are  volatilized  into 
the  air  of  the  workshop,  with  fatal  results. 

Arsenic  trioxide  is  capable  of  existing,  and  occurs  in  commerce,  in 
two  distinct  allotropic  conditions  :  crystallized  or  "powdered"  and  vitre- 
ous. When  freshly  resublimed,  it  appears  in  colorless  or  faintly  yellow, 
transparent,  vitreous  masses,  having  no  visible  crystalline  structure. 
Shortly,  however,  these  masses  become  opaque  upon  the  surface,  and 
present  the  appearance  of  porcelain  ;  this  change,  which  is  due  to  the 


AKSENIC   TRIOXIDE, 


119 


substance  assuming  the  crystalline  form,  gradually  and  slowly  progresses 
toward  the  centre  of  the  mass,  which,  however,  remains  vitreous  for  a 
long  time.  The  change  is  attended  by  the  slow  liberation  of  heat,  and,  if 
it  be  made  to  take  place  more  rapidly,  a  faint  light  is  visible  in  obscurity. 
Whenever  arsenic  trioxide  is  sublimed,  if  the  vapors  be  condensed  upon 
a  cool  surface,  it  is  deposited  in  the  form  of  brilliant  octahedral  crystals, 
which  are  larger  and  more  perfect  the  nearer  the  temperature  of  the 
condensing  surface  is  to  180°.  The  crystalline  variety  may  be  converted 
into  the  vitreous  by  keeping  it  for  some  time  at  a  temperature  near  its 
point  of  volatilization. 

The  taste  of  arsenic  trioxide  is  at  first  faintly  sweet,  afterward  acrid, 
metallic,  and  nauseating.  It  is  odorless;  in  aqueous  solution  (see  below) 
it  has  a  faintly  acid  reaction.  The  specific  gravity  of  the  vitreous  variety 
is  3.689;  that  of  the  crystalline,  3.785. 

The  solubility  of  this  substance  in  water  and  in  other  fluids  has  been 
the  subject  of  many  investigations.  In  pure  water,  arsenic  trioxide  dis- 
solves as  arsenious  acid  (q.  v.);  the  amount  dissolved  depends  upon  the 
temperature,  the  method  of  making  the  solution,  and  the  nature  of  the 
oxide.  Thus,  Bussy  found  that  water  at  13°  is  capable  of  dissolving  forty 
grams  of  the  vitreous  oxide,  but  only  twelve  to  thirteen  grams  of  the 
crystalline  to  the  litre  ;  he  found  also  that,  by  prolonged  boiling  with 
water,  the  crystalline  variety  is  converted  into  the  vitreous,  or,  at  all 
events,  the  solubility  of  the  two  varieties  becomes  the  same — one  hundred 
and  ten  grams  to  the  litre  of  boiling  water.  According  to  Taylor,  cold 
water  dissolves  from  one  to  two  grams  per  litre  only;  boiling  water,  when 
poured  upon  the  oxide  and  allowed  to  cool,  dissolves  2.5  parts  in  one 
thousand;  and  water  boiled  upon  the  oxide,  twenty-five  parts  per  one 
thousand.  These  results  are  probably  too  low,  although  those  for  cold 
water  agree  well  with  the  figures  given  by  Woodman  and  Tidy,  which 
represent  the  latest  experiments  upon  the  subject,  and  are  given  below: 


Transparent  form. 

Opaque  form. 

Fresh  crystalline 
oxide. 

1,000  parts  of  cold  distilled  water,  after 
standing  24  hours,  dissolved  .... 

1.74  parts. 

1.1  6  parts. 

2.0  parts. 

1,000  parts  of  boiling  water  poured  on 
the  oxide,  and  allowed  to  stand  for 
24  hours,  dissolved  .... 

10  12  parts. 

5  .  4   parts. 

15  0  parts 

1,000  parts  of  water  boiled  for  one  hour, 
the  quantity  being  kept  uniform  by 
the  addition  of  boiling  water  from 
time  to  time,  and  filtered  immedi- 
ately, dissolved  

64  5   parts 

76  5    parts 

87  0  parts 

These  results  for  boiling  water  agree  better  with  those  of  Bussy  than 
with  those  of  Taylor. 

The  solution  of  the  crystallized  oxide  in  cold  water  is  always  very 
slow  (the  vitreous  oxide  dissolves  more  rapidly),  and  continues  for  a  long 
time.  If  white  arsenic  be  thrown  upon  cold  water,  only  a  portion  of  it 
sinks,  the  remainder  floating  upon  the  surface,  notwithstanding  its  high 
specific  gravity.  This  is  due  to  a  repulsion  of  the  water  from  the  sur- 
faces of  the  crystals,  which  also  accounts,  to  some  extent  at  least,  for  its 
slow  solution.  Even  after  several  days  cold  water  does  not  dissolve  all 


120  GENERAL    MEDICAL    CHEMISTRY. 

the  oxide  with  which  it  is  in  contact.  Gmelin  has  shown  that  if  one  part 
of  oxide  be  digested  with  eighty  parts  of  water,  at  ordinary  temperatures 
for  several  days,  the  resulting  solution  contains  -^  ;  with  160  parts  water, 
•j^-g- ;  with  240  parts,  -g-J-g-  ;  with  1,000  parts  water,  y-2Vo  ;  and  that,  even 
when  16,000  or  100,000  parts  of  water  are  used,  a  portion  of  the  oxide  re- 
mains undissolved.  The  same  author- has  shown  that  arsenious  oxide, 
which  has  remained  in  contact  with  cold  water  in  closed  vessels  for  eigh- 
teen years,  dissolves  to  the  extent  of  1  part  in  54  of  water,  or  18.5  parts 
in  1,000,  which  may  be  given  as  the  maximum  solubility  of  the  crystal- 
lized oxide  in  cold  water. 

The  power  of  water  of  holding  the  acid  in  solution,  once  it  is  dissolved, 
is  not  the  same  as  its  power  of  dissolving  it.  If  a  concentrated  solution 
be  made  by  boiling  water  upon  the  oxide  and  filtering  hot,  the  filtrate  may 
be  evaporated  down  to  one-half  its  original  bulk  without  depositing  any 
of  the  acid,  of  which  this  concentrated  fluid  now  contains  as  much  as  one 
part  in  six  of  water,  or  166.6  parts  per  1,000.  If  a  hot  solution  of  the 
acid  be  allowed  to  cool,  the  solution  will  contain  62.5  parts  per  1,000  at 
16°,  and  50  parts  per  1,000  at  7°. 

The  solubility  of  the  oxide  in  alcohol  varies  with  the  strength  of  the 
spirit  and  the  nature  of  the  oxide,  the  vitreous  variety  being  more  soluble 
in  strong  than  in  weak  alcohol,  while  the  contrary  is  the  case  with  the 
crystalline,  as  is  shown  in  the  following  table : 

1  ruin        *-    /i  •      i  Alcohol  at         Alcohol  at         Alcohol  at         Absolute 

1,000  parts  dissolve  56  per  cent.       79  per  cent.       86  per  cent.          alcohol. 

(At  15° 16.80  14.30  7.15  0.25 

Crystallized  oxide  -I  At  the  boiling- 

(  point 48.95  45.51  31.97  34.02 

Vitreous  oxide  at  15° 5.04  5.40  10.60 

The  presence  of  the  mineral  acids  and  alkalies,  ammonia  and  ammoni- 
acal  salts,  alkaline  carbonates,  tartaric  acid,  and  the  tartrates,  increases 
the  solubility  of  arsenic  trioxide  in  water. 

A  solution  of  the  acid  in  dilute  hydrochloric  acid  is  officinal — Liquor  ar- 
senici  hydrochloricus  (U.  S.,  Br.),  and,  when  made  according  to  the  direc- 
tions of  the  Pharmacopeia,  does  not  contain  arsenic  trichloride,  but  is  sim- 
ply a  solution  of  arsenious  acid  in  diluted  hydrochloric  acid. 

Arsenic  trioxide  is  less  soluble  in  fluids  containing  fats  or  extractive 
or  other  organic  matters  (the  various  liquid  articles  of  food),  than  it  is  in 
pure  water. 

In  chemico-legal  cases,  in  which  the  question  of  the  solubility  of  arsenic 
is  very  likely  to  arise,  it  must  not  be  forgotten  that  the  quantity  of  arsenic 
trioxide  which  a  person  may  unconsciously  take  in  a  given  quantity  of 
fluid  is  not  limited,  under  certain  circumstances,  to  that  which  the  fluid  is 
capable  of  dissolving'  a  much  greater  quantity  than  this  may  be  taken 
while  in  suspension  in  the  liquid,  especially  if  it  be  mucilaginous. 

Arsenic  trioxide  is  readily  decomposed  by  reducing  agents,  elementary 
arsenic  being  deposited,  a  decomposition  which  occurs  when  it  is  heated 
with  hydrogen,  carbon,  potassium  cyanide,  etc. ;  and  at  a  lower  tempera- 
ture by  more  active  reducing  agents.  Oxydizing  agents,  on  the  other 
hand,  such  as  nitric  acid,  the  hydrates  of  chlorine,  chromic  acid,  etc.,  con- 
vert it  into  arsenic  pentoxide,  or  arsenic  acid. 

Its  solution,  acidulated  with  hydrochloric  acid,  is  decomposed  when 
boiled  with  metallic  copper,  and  an  alloy  of  copper  and  arsenic  is  de- 


ARSENIC    ACIDS.  121 

posited  as  a  gray  film  upon  the  copper  (see  p.  127).  Arsenic  trioxide  is 
largely  used  in  the  arts,  in  the  manufacture  of  glass,  green  pigments, 
and  vermin-poisons;  in  the  processes  of  dyeing,  in  the  preservation  of 
anatomical  preparations,  and  by  the  taxidermist.  It  is  one  of  the  com- 
monest of  poisons  (see  p.  125). 


Arsenic  Pentoxide. 

Arsenic  anhydride — As2O5 — is  obtained  by  heating  arsenic  acid  to 
redness.  It  is  a  white,  amorphous  solid,  which,  when  exposed  to  the  air, 
slowly  absorbs  moisture.  It  is  fusible  at  a  dull  red  heat,  and  at  a  slightly 
higher  temperature  decomposes  to  arsenic  trioxide  and  oxygen.  It 
dissolves  slowly  in  water,  forming  arsenic  acid,  AsO4H3. 


Arsenic  Acids. 

These  substances  form  a  series,  resembling  the  corresponding  com- 
pounds of  phosphorus.  No  arsenic  compound  corresponding  to  hypo- 
phosphorous  acid  has,  however,  been  discovered  as  yet: 

Arsenious  acid AsO3H3. 

Arsenic  acid AsO4H3. 

Pyroarsenic  acid As2O7H4. 

Metarsenic  acid AsO3H. 

Arsenious  acid,  AsO3H3. — Although  this  acid  has  not  been  sepa- 
rated, its  existence  in  solutions  of  the  trioxide  may  be  presumed,  espe- 
cially as  the  solution  has  a  faintly  acid  reaction.  Its  composition  is  similar 
to  that  of  phosphorous  acid,  and,  as  is  the  case  with  that  acid,  two  only 
of  the  atoms  of  hydrogen  are  replaceable.  Corresponding  to  this  acid 
are  a  number  of  important  salts,  called  arsenites,  which  have  the  general 
composition  AsO3HM'2,  AsO3HM",  (AsO3)2H4M". 

Arsenites  have  also  been  obtained  which  seem  to  correspond  to  a 
pyroarsenious  acid,  As2O5H4,  and  others  corresponding  to  a  metarsenious 
acid,  AsO2H. 

Arsenic  acid —  Orthoarsenic  acid — AsO4H3 — is  obtained  by  oxidizing 
arsenic  trioxide  with  nitric  acid,  in  the  presence  of  water: 

As2O3  +  2H20  +  2NO3H = 2  AsO4H3  +  N2O3. 

The  oxidation  may  also  be  brought  about  by  chlorine,  aqua  regia,  or 
other  oxidizing  agents.  A  syrupy  solution  is  thus  obtained  which,  at 
15°  or  below,  becomes  semi-solid  from  the  formation  of  transparent  crys- 
tals, containing  one  molecule  of  water  of  crystallization.  These  crystals, 
which  are  very  deliquescent  and  closely  resemble  in  appearance  those  of 
sodium  sulphate,  lose  their  water  of  crystallization  when  heated  to  100°, 
and  form  a  white,  pasty  mass  composed  of  minute  crystalline  needles, 
which  are  anhydrous. 

Arsenic  acid  is  very  soluble  in  water,  the  solution  being  strongly  acid 
in  taste  and  in  reaction;  colorless  and  odorless. 

In  the  presence  of  nascent  hydrogen,  arsenic  acid  is  decomposed  with 
formation  of  water  and  hydrogen  arsenide.  It  is  readily  converted  into 


122  GENERAL    MEDICAL    CHEMISTRY. 

the  lower  stage  of  oxidation  of  arsenic  by  the  action  of  reducing  agents. 
A  current  of  sulphur  dioxide  passed  through  its  solution  converts  it  into 
arsenious  acid.  If  hydrogen  sulphide  be  passed  through  a  solution  of 
arsenic  acid  or  of  an  arsenate,  the  first  portions  of  the  gas  reduce  the 
arsenical  compound  to  arsen.ious  acid,  while  sulphur  separates.  After 
this  action  has  occurred,  the  arsenious  acid  is  itself  decomposed,  with 
formation  of  arsenic  trisulphide. 

Hydrochloric  acid,  even  when  concentrated  and  boiling,  forms  with 
arsenic  acid  mere  traces  of  arsenic  trichloride. 

Like  phosphoric  acid,  arsenic  acid  is  tribasic;  and  the  arsenates  re- 
semble the  phosphates  in  composition,  and  in  many  of  their  chemical  and 
physical  properties. 

Although  not  as  poisonous  as  arsenious  acid  (Woehler  and  Frerichs) 
in  solutions  of  equal  strength,  it  is  quite  as  dangerous  a  substance,  owing 
to  its  greater  solubility.  It  is  manufactured  in  large  quantities  industri- 
ally, and  is  used  in  dyeing  and  in  the  manufacture  of  fuchsine  (q.  v.). 

Pyroarsenic  acid,  As2O7H4. — The  resemblance  between  the  phos- 
phorus acids  and  those  of  arsenic  is  visible  in  the  action  of  heat  upon 
arsenic  acid,  as  well  as  in  other  properties.  If  arsenic  acid  be  heated  to 
140°-180°,  there  form  compact  masses  of  hard  crystals  having  the  above 
composition,  and  formed,  like  pyrophosphoric  acid,  by  the  union  of  two 
molecules  of  the  orthoacid  with  separation  of  the  elements  of  one  mole- 
cule of  water.  This  acid  is  quite  unstable  and  readily  takes  up  the  ele- 
ments of  water  again,  with  regeneration  of  orthoarsenic  acid;  for  this 
reason  it  is  not  soluble  in  water  without  decomposition.  It  forms  salts 
having  the  same  constitution  as  the  pyrophosphates. 

Metarsenic  acid,  AsO3H. — If  pyroarsenic  (or  arsenic)  acid  be  main- 
tained at  a  temperature  of  200°-206°  for  some  time,  a  further  loss  of 
water  occurs,  and  an  acid  is  formed  having  the  composition  AsO3H,  the 
transformation  taking  place  rather  suddenly.  It  appears  in  the  form  of 
white,  pearly  crystals,  which  dissolve  readily  in  water,  the  act  of  solution 
being  attended  with  a  considerable  elevation  of  temperature  and  the  re- 
generation of  arsenic  acid.  It  is  a  monobasic  acid. 


Compounds  of  Arsenic  and  Sulphur. 

Quite  a  number  of  compounds  of  these  elements  have  been  described, 
some  of  which  are  more  probably  mixtures  than  definite  compounds. 
Three,  however,  are  well  characterized: 

Arsenic  disulphide As2S2. 

Arsenic  trisulphide As2S3. 

Arsenic  pentasulphide As2S5. 

Arsenic  disulphide — Red sulphide  of  arsenic — Healgar — Red  orpiment 
— -Ruby  sulphur — Red  sulp/mret  of  arsenic — Sandarach — As2SQ. — Exists 
in  nature  in  the  form  of  translucent,  ruby-red  crystals.  It  is  also  prepared 
artificially  by  fusing  together  seventy-five  parts  of  arsenic  and  thirty-two 
parts  of  sulphur,  or  by  heating  a  mixture  of  sulphur  and  arsenic  trioxide;  as 
so  prepared  it  appears  in  brick-  or  ruby-red  fragments,  having  a  conchoidal 
fracture.  It  is  fusible,  insoluble  in  water,  but  soluble  in  solutions  of  the 
alkaline  sulphides  and  in  a  boiling  solution  of  potassium  hydrate.  It  is 
used  in  the  arts,  in  pyrotechny,  and  as  a  pigment. 


COMPOUNDS    OF    ARSENIC.  123 

Arsenic  trisulphide —  Orpiment — Auripigmentum —  Yellow  sulphide  or 
Sulphuret  of  arsenic — King^s  yellow — As2S3. — Occurs  in  nature  in  bril- 
liant, golden  yellow  flakes.  Obtained  artificially  by  passing  hydrogen  sul- 
phide through  a  solution  of  arsenious  acid,  or  by  heating  a  mixture  of 
arsenic  and  sulphur,  or  of  arsenic  trioxide  and  sulphur. 

It  is  a  lemon-yellow  powder  when  obtained  by  precipitation,  and  in 
orange-yellow  crystalline  masses  when  prepared  by  sublimation. 

It  is  almost  insoluble  in  cold  water,  but  sufficiently  soluble  in  hot  water 
to  communicate  to  it  a  distinctly  yellow  color.  By  continued  boiling  with 
water  it  is  decomposed,  with  formation  of  hydrogen  sulphide  and  arse- 
nious acid.  The  limited  solution  of  this  substance  in  water  does  not  take 
place  in  the  presence  of  a  small  quantity  of  hydrogen  sulphide.  It  is  in- 
soluble in  dilute  hydrochloric  acid,  but  very  soluble  in  solutions  of  the  al- 
kaline hydrates,  especially  in  solution  of  ammonium  hydrate,  and  in  so- 
lutions of  the  alkaline  carbonates  and  sulphides. 

Nitric  acid  oxidizes  it  quickly,  forming  arsenic  and  sulphuric  acids. 
The  same  decomposition  occurs  with  nitrohydrochloric  acid,  and  with 
hydrochloric  acid  and  potassium  chlorate. 

Arsenic  trisulphide  corresponds  in  constitution  to  the  trioxide,  atoms 
of  sulphur  taking  the  place  of  those  of  oxygen.  Like  that  body,  it  may 
be  regarded  as  an  anhydride,  although  it  contains  no  oxygen;  for,  not- 
withstanding the  fact  that  sulpharsenious  acid,  AsS3H3,  has  not  been  sepa- 
rated, its  existence  must  be  regarded  as  possible  from  that  of  the  well- 
characterized  sulpharsenites,  pyrosulpharsenites,  and  metasulpharsenites, 
similar  in  constitution  to  the  salts  of  the  corresponding  oxygen  acids. 

Orpiment  is  used  in  the  arts  as  a  pigment,  under  the  name  of  King's 
yellow,  and,  as  such,  has  given  rise  to  many  cases  of  so  called  "  accidental  " 
poisoning,  by  being  mistaken  for  more  harmless  coloring  matters  and 
introduced  into  articles  of  food  with  more  or  less  innocent  intent.  Al- 
though the  natural  product  is  probably  inert,  the  artificial  is  actively 
poisonous,  from  the  presence  in  it  of  arsenic  trioxide.  In  cases  of  death 
from  arsenical  poisoning,  the  arsenic  is  liable  to  be  converted  into  the 
trisulphide,  after  long  burial. 

Arsenic  pentasulphide,  As^  —  is  said  to  have  been  obtained  by 
fusing  a  mixture  of  the  trisulphide  and  sulphur  in  proper  proportions, 
as  a  yellow,  fusible  solid,  capable  of  sublimation  in  the  absence  of  air. 
The  precipitate  which  is  formed  when  a  solution  of  an  arsenate  is 
treated  with  hydrogen  sulphide  is  not  this  substance,  but  a  mixture  of  the 
trisulphide  and  sulphur.  Whether  or  no  this  body  exists  in  the  free  state 
(and  its  existence  has  been  called  in  question),  there  exist  well-defined 
salts,  sulpharsenates,  pyrosulpharsenates,  and  metasulpharsenates,  to 
which  this  body  bears  the  same  relation  that  arsenic  pentoxide  does  to- 
the  corresponding  oxygen  compounds. 


Compounds  of  Arsenic  -with  the  Elements  of  the  Chlorine 

Group. 

Arsenic  trifluoride,  AsF3 — a  colorless,  fuming  liquid,  boiling  at  63 % 
capable  of  attacking  glass,  obtained  by  distilling  a  mixture  of  arsenic 
trioxide,  fluorspar,  and  sulphuric  acid. 

Arsenic  trichloride,  AsCl3. — Obtained  by  distilling  a  mixture  of 
arsenic  trichloride,  sulphuric  acid,  and  sodium  chloride,  using  a  well- 
cooled  receiver. 


124  GENERAL    MEDICAL    CHEMISTRY. 

It  is  a  colorless  liquid,  boils  at  134°,  fumes  when  exposed  to  the  air, 
and  volatilizes  readily  at  temperatures  below  its  boiling-point.  Its  for- 
mation must  be  avoided  in  processes  for  the  chemico-legal  detection  of 
.arsenic,  lest  it  be  volatilized  and  lost. 

It  is  formed  by  the  action,  of  hydrochloric  acid,  even  when  compara- 
tively dilute,  upon  arsenic  trioxide  at  tbrfe  temperature  of  the  water-bath  ; 
but,  if  potassium  chlorate  be  added,  the  trioxide  is  oxidized  to  arsenic 
.acid,  and  the  formation  of  the  chloride  thus  prevented.  Arsenic  trioxide, 
when  fused  with  sodium  nitrate,  is  converted  into  sodium  arsenate,  which 
is  not  volatile  ;  if.  however,  small  quantities  of  chlorides  be  present, 
arsenic  trichloride  is  formed  (see  p.  129).  It  is  highly  poisonous. 

Arsenic  tribromide,  AsBr3. — Obtained  by  adding  powdered  arsenic 
to  bromine,  and  distilling  the  product  at  220°.  A  solid,  colorless,  crys- 
talline body,  fuses  at  20°-25°,  boils  at  220°,  and  is  decomposed  on  con- 
tact with  water. 

Arsenic  triiodide,  AsI3. — Obtained  by  adding  arsenic  to  a  solution  of 
iodine  in  carbon  disulphide,  or  by  fusing  together  arsenic  and  iodine  in 
proper  proportions.  •  A  brick-red  solid,  fusible  and  capable  of  volatilizing 
unchanged.  In  a  large  quantity  of  water  it  dissolves  ;  with  a  small 
quantity  it  is  decomposed,  with  formation  of  hydriodic  acid,  arsenic  tri- 
oxide, water,  and  a  residue  of  arsenic  triiodide. 

Arsenic  triiodide,  prepared  by  fusion,  is  officinal  as  Arsenici  iodidum, 
(U.  S.),  and  enters  into  the  composition  of  the  Liq.  arsenici  et  hydrargyri 
iodidi  (U.  S.),  or  Donovan's  solution. 


Action  of  Arsenical  Compounds  upon  the  Animal  Economy. 

The  poisonous  nature  of  many  of  the  arsenical  compounds  has  been 
known  from  a  remote  period,  and  it  is  probable  that  more  murders  have 
been  committed  by  their  use  than  by  that  of  all  other  toxic  substances 
combined.  Even  at  the  present  time — notwithstanding  the  fact  that,  sus- 
picion once  aroused,  the  detection  of  arsenic  in  the  dead  body  is  certain 
and  comparatively  easy — criminal  arsenical  poisoning  is  still  quite  com- 
mon, especially  in  rural  districts.  It  would  seem,  however,  that  in  France, 
phosphorus  is  more  frequently  used  ;  while  in  England,  opium  and  its 
preparations  are  the  favorite  agents  of  the  poisoner. 

Of  poisons  used  by  suicides  in  this  country,  the  arsenical  compounds 
(especially  Paris  green,  aceto-arsenite  of  copper)  maintain  their  posi- 
tion at  the  head  of  the  list.  The  great  majority  of  cases  of  arsenical 
poisoning  which  come  to  our  notice  are  suicidal  ;  we  are  forced,  however, 
by  statistics  and  experience,  to  believe  that  this  proportion  would  be  much 
reduced  were  it  not  that  the  secrecy  enshrouding  homicidal  poisoning  is 
only  penetrated  in  a  small  percentage  of  cases — not  from  the  fault  of  the 
chemist,  but  from  that  of  physicians,  coroners,  and  other  prosecuting 
officers.* 

The  poison  usually  enters  the  circulation  by  the  alimentary  canal, 
being  taken  by  the  mouth;  but  instances  are  not  wanting  in  which  it  has 

*  The  last  conviction  of  the  crime  of  murder  by  poison  in  New  York  City  was  that 
of  Stephens,  in  1858.  During  the  following  period  of  nearly  a  quarter  of  a  century, 
Paris  and  London  have  witnessed  many  trials  of  cases  of  homicidal  poisoning,  while 
New  York  would  seem  to  be  either  free  from  the  crime,  or  a  safe  place  for  those  who 
desire  to  murder  in  this  way. 


ACTION    OF   AKSENICAL    COMPOUNDS.  125 

been  introduced  in  other  ways:  by  the  skin,  to  which  it  has  been  applied 
in  the  form  of  ointment;  by  abraded  surfaces,  to  which  it  has  been  ap- 
plied by  quacks  as  a  "  cancer  cure;"  by  the  rectum,  vagina,  or  male 
urethra. 

The  substances  taken  or  administered  have  been: 

First. — Elementary  arsenic,  usually  in  the  shape  of  fly-poison,  which,, 
however,  contains  arsenic  trioxide  as  well.  Elementary  arsenic  is  not 
poisonous  so  long  as  it  remains  such;  in  contact  with  water,  or  with  the 
saliva,  however,  it  is  converted  into  an  oxide,  which  is  then  dissolved, 
and,  being  capable  of  absorption,  produces  the  characteristic  effects  of 
the  arsenical  compounds. 

Second. — Hydrogen  arsenide,  the  most  actively  poisonous  of  the  in- 
organic compounds  of  arsenic,  has  not  been  used  by  the  homicide  or  the- 
suicide.  Several  cases  of  accidental  death  from  its  effects  have  been 
recorded,  prominent  among  which  is  that  of  the  chemist  Gehlen,  who- 
died  in  consequence  of  having  inhaled  a  few  bubbles  of  the  gas  while  ex- 
perimenting upon  it.  In  other  cases  death  has  followed  the  inhalation 
of  hydrogen,  made  from  zinc,  or  sulphuric  acid  contaminated  with  arsenic^ 

Third. — Arsenic  trioxide  has  been  the  substance  administered  in  a- 
great  number  of  cases  of  homicidal  poisoning,  has  been  used  to  a  limited 
extent  by  suicides,  and  has  been  frequently  taken  or  administered  by 
mistake  or  accident.  It  has  been  given  by  every  channel  of  entrance  to 
the  circulation;  in  some  instances  concealed  with  great  art,  in  others^ 
merely  held  in  suspension  by  stirring  in  a  transparent  fluid  given  to  an 
intoxicated  person.  If  the  poison  have  been  given  in  quantity,  and  un- 
dissolved,  it  may  be  found  in  the  stomach  after  death  in  the  form  of 
eight-sided  crystals,  more  or  less  worn  by  the  action  of  the  solvents  with 
which  it  has  come  in  contact. 

The  lethal  dose  is  variable,  death  having  occurred  from  two  and  one- 
half  grains,  and  recovery  having  followed  the  taking  of  a  dose  of  two 
ounces.  It  is  more  active  when  taken  fasting  than  when  taken  on  a  full 
stomach,  in  which  latter  case  all,  or  nearly  all,  the  poison  is  frequently 
expelled  by  vomiting,  before  there  has  been  time  for  the  absorption  of 
more  than  a  small  quantity. 

Fourth. — Potassium  arsenite,  the  active  substance  in  "  Fowler's  solu- 
tion," although  largely  used  by  the  laity  in  malarial  districts  as  an  ague- 
cure,  has,  so  far  as  the  records  show,  produced  but  one  case  of  fatal  poi- 
soning. 

Fifth. — Sodium  arsenite  is  sometimes  used  to  clean  metal  vessels,  a 
practice  whose  natural  results  are  exemplified  in  the  death  of  an  individual 
who  drank  beer  from  a  pewter  mug  so  cleaned;  and  in  the  serious  illness 
of  three  hundred  and  forty  children  in  an  English  institution,  in  which 
this  material  had  been  used  for  cleaning  the  water-boiler. 

Sixth — Arsenic  acid  and  arsenates. — The  acid  itself  has,  so  far  as  we 
know,  been  directly  fatal  to  no  one.  The  cases  of  death  and  illness, 
however,  which  have  been  put  to  the  account  of  the  red  anilin  dyes,  are 
not  due  to  them  directly,  but  to  arsenical  residues  remaining  in  them  as 
the  result  of  careless  processes  of  manufacture. 

Seventh. — Sulphides  of  arsenic. — Poisoning  by  these  is  generally  due- 
to  the  use  of  orpiment,  introduced  into  articles  of  food  as  a  coloring  mat- 
ter, by  a  combination  of  fraud  and  stupidity,  in  mistake  for  turmeric. 

Eighth. — The  arsenical  greens. — Scheele's  green  or  cupric  arsenite,. 
and  Schweinfurth  green  or  cupric  aceto-metarsenite  (the  latter  com- 
monly known  in  the  United  States  as  Paris  green,  a  name  applied  in 


126  GENERAL    MEDICAL    CHEMISTRY. 

Europe  to  one  of  the  anilin  pigments).  These  substances,  although 
rarely  administered  \vith  murderous  intent,  have  been  the  cause  of  death 
in  a  great  number  of  cases.  Among  suicides  in  the  lower  orders  of  the 
population  in  large  cities,  Paris  green  has  been  the  favorite. 

The  arsenical  pigments  may  also  produce  disastrous  results  by  "  acci- 
dent;" by  being  incorporated  in  ornamental  pieces  of  confectionery;  by 
being  used  in  the  dyeing  of  textile  fabrics,  from  which  they  may  be  easily 
rubbed  off;  and  by  being  used  in  the  manufacture  of  wall-paper.  Many 
instances  of  chronic  or  subacute  arsenical  poisoning  have  resulted  from  in- 
habiting rooms  hung  with  paper  whose  whites,  reds,  or  greens  were  pro- 
duced by  arsenical  pigments.  From  such  paper  the  poison  is  disseminated 
in  the  atmosphere  of  the  room  in  two  ways:  either  as  an  impalpable 
powder,  mechanically  detached  from  the  paper  and  floating  in  the  air,  or, 
as  Fleck  has  shown,  by  their  decomposition,  and  the  consequent  diffusion 
of  volatile  arsenical  compounds  in  the  air. 

The  treatment  in  acute  arsenical  poisoning  is  the  same,  whatever  may 
be  the  form  in  which  the  poison  has  been  taken.  The  first  indication  is 
the  removal  of  any  unabsorbed  poison  from  the  alimentary  canal.  If 
vomiting  have  not  occurred  from  the  effects  of  the  toxic,  it  should  be  in- 
duced by  the  administration  of  zinc  sulphate,  or  by  mechanical  means. 
The  stomach-pump  should  not  be  used  unless  the  case  is  seen  soon  after 
the  taking  of  the  poison.  When  the  stomach  has  been  emptied,  the 
chemical  antidote  is  to  be  administered,  with  a  view  to  the  transforma- 
tion in  the  stomach  of  any  remaining  arsenical  compound  into  the  insolu- 
ble, and,  therefor,  innocuous  ferrous  arsenate.  From  recent  experi- 
ences, it  would  seem  that  the  preparation  known  as  "  dialyzed  iron  "  is 
very  efficacious;  failing  this,  ferric  hydrate  must  be  prepared  extempo- 
raneously, as  when  dry  or  not  recently  prepared  it  has  no  longer  the  power 
of  combining  with  the  arsenical  compound.  To  prepare  this  substance  a 
solution  of  ferric  sulphate,  Liq.  ferri  tersulphatis  (U.  S.)  =  Liq.  ferri 
persulphatis  (Br.),  is  diluted  with  three  volumes  of  water  and  treated  with 
aqua  ammonite  in  slight  excess.  The  precipitate  formed  is  collected  upon 
a  muslin  filter  and  washed  with  water  until  the  washings  are  nearly  taste- 
less. The  contents  of  the  filter — Ferri  oxidum  liydratum  (U.  S.),  Ferri 
peroxidum  humidum^  (Br.) — are  to  be  administered,  while  still  moist,  in 
frequently  repeated  doses  of  one  or  two  teaspoonf uls  until  the  faeces  become 
black  or  very  dark  in  color  from  the  presence  of  ferrous  sulphide.  This 
treatment  applies  only  to  those  cases  in  which  the  poison  has  been  taken 
by  the  mouth,  and  has  for  its  object  the  removal  of  those  portions  which 
are  not  yet  absorbed.  The  symptoms  caused  by  the  absorbed  poison  are 
to  be  treated  as  they  arise. 


Toxicological  Analysis. 

PRECAUTIONS  TO  BE  TAKEN  BY  THE  PHYSICIAN. — It  will  rarely  happen 
that  in  a  case  of  suspected  homicidal  poisoning  by  arsenic,  or  by  other 
poisons,  the  physician  in  charge  will  be  willing  or  competent  to  conduct 
the  chemical  analysis  upon  which  probably  the  conviction  or  acquittal  of 
the  accused  will  mainly  depend.  Upon  his  knowledge  and  care,  however, 
the  success  or  futility  of  the  chemist's  labors  depend  in  a  great  measure. 

It  is,  as  a  rule,  the  physician  who  first  suspects  foul  play;  and,  while  it 
is  undoubtedly  his  duty  to  avoid  any  public  manifestation  of  his  suspicion, 
it  is  just  as  certainly  his  duty  toward  his  patient  and  toward  the  com- 


TOXICOLOGICAL    ANALYSIS.  127 

munity  to  satisfy  himself  as  to  the  truth  or  falsity  of  his  suspicion  by  the 
application  of  a  simple  test  to  the  excreta  of  the  patient  during  life,  the 
result  of  which  may  enable  him  to  prevent  a  crime,  or,  failing  that,  take 
the  first  step  toward  the  punishment  of  the  criminal. 

In  a  case  in  which,  from  the  symptoms,  the  physician  suspects  poison- 
ing by  any  substance,  he  should  himself  test  the  urine  or  fasces,  or  both, 
and  govern  his  treatment  and  his  actions  toward  the  patient,  and  those 
surrounding  the  patient,  by  the  results  of  his  examination.  Should  the 
case  terminate  fatally,  he  should  at  once  communicate  his  suspicions  to 
the  prosecuting  officer,  and  require  a  post-rnortem  investigation,  which 
should,  if  at  all  possible,  be  conducted  in  the  presence  of  the  chemist  who 
is  to  conduct  the  analysis;  for,  be  the  physician  as  skilled  as  he  may  be, 
there  are  odors  and  appearances,  observable  in  many  cases  at  the  opening 
of  the  body,  full  of  meaning  to  the  toxicological  chemist,  which  are  ephem- 
eral, and  whose  bearing  upon  the  case  is  not  readily  recognized  by  those 
not  thoroughly  experienced. 

Cases  frequently  arise  in  which  it  is  impossible  to  bring  the  chemist 
upon  the  ground  in  time  for  the  autopsy;  in  such  cases  the  physician  should 
remember  that  that  portion  of  the  poison  remaining  in  the  alimentary 
tract  (we  are  speaking  of  true  poisons)  is  but  the  residue  of  the  dose  in 
excess  of  that  which  has  been  necessary  to  produce  death;  and,  if  the  pro- 
cesses of  elimination  have  been  active,  there  may  remain  no  trace  of  the 
poison  in  the  alimentary  canal,  while  it  still  may  be  detectable  in  deeper- 
seated  organs.  Moreover,  the  finding  of  poison  in  the  stomach  alone  would 
not,  at  the  present  time,  be  sufficient  to  procure  conviction  of  the  crimi- 
nal, who  might  raise  the  very  plausible  question  as  to  whether  the  poison 
was  not  injected  by  some  malicious  person  into  that  viscus  after  death. 

For  these  reasons  it  is  not  sufficient  to  send  the  stomach  alone  for 
analysis;  the  chemist  should  also  receive  the  entire  intestinal  canal,  at 
least  one-half  the  liver,  the  spleen,  one  or  both  kidneys,  a  piece  of  muscu- 
lar tissue,  the  brain,  and  any  urine  that  may  remain  in  the  bladder.  The 
intestinal  canal  should  be  removed  and  sent  to  the  chemist  without  hav- 
ing been  opened,  and  with  ligatures  enclosing  the  contents  at  the  two  ends 
of  the  stomach  and  at  the  lower  end  of  the  intestine.  The  brain  and  ali- 
mentary canal  are  to  be  placed  in  separate  jars,  and  the  other  viscera  in 
another  jar  together;  the  urine  in  a  vial  by  itself.  All  of  these  vessels 
are  to  be  new  and  clean,  and  are  to  be  closed  by  new  corks,  or  by  glass 
stoppers,  or  covers  (not  zinc  screw-caps),  which  are  then  coated  with  paraf- 
finey(not  sealing-wax),  and  so  fastened  with  strings  and  seals  that  it  is  im- 
possible to  open  the  vessels  without  cutting  the  strings  or  breaking  the 
seals.  If  the  physician  fail  to  observe  these  precautions,  he  has  probably 
made  the  breach  in  the  evidence  through  which  the  criminal  will  escape, 
and  has  at  the  outset  defeated  the  aim  of  the  analysis. 

Toxicological  analysis. — Since  the  earlier  days  of  toxicological  chem- 
istry many  processes  for  the  detection  of  arsenic  have  been  suggested, 
varying  greatly  as  to  the  facility  of  their  application  and  the  reliability  of 
the  results  obtained. 

Of  these  there  is  one  which,  although  well  adapted  to  the  use  of  phy- 
sicians during  the  life  of  the  patient,  is  of  little  value  from  a  chemico- 
legal  point  of  view  ;  we  refer  to  Keinsch's  test. 

The  advantages  of  this  method  are  that  it  may  be  applied  to  solutions 
containing  organic  matter,  the  urine  for  instance  ;  it  is  easily  conducted, 
and  its  positive  results  are  not  misleading,  if  the  test  be  carried  to  com- 
pletion. It  is,  therefor,  the  test  which  we  should  recommend  physicians 


128  GENERAL    MEDICAL    CIIEMISTUY. 

to  apply  to  the  urine,  in  cases  which  they  suspect  are  due  to  arsenical 
poisoning  ;  but  at  the  same  time  it  is  one  whose  application  to  any  solid 
or  fluid,  after  death,  we  should  disapprove  of  strongly,  unless  complete  evi- 
dence of  the  presence  of  the  poison  had  already  been  obtained  by  the  use 
of  other  tests.  By  its  use  copper  is  introduced  into  the  substances  ex- 
amined, which  may  seriously  interfere  with  subsequent  steps  in  the 
analysis,  by  rendering  impossible  a  distinction  between  poisoning  by 
arsenious  anhydride  and  that  by  Paris  green — a  distinction  which  may 
become  of  vital  importance  if  the  defence  claim  the  case  to  be  one  of 
suicide.  Other  disadvantages  of  Reinsch's  test  are- that  it  is  not  as  deli- 
cate as  Marsh's  test  ;  that  by  it  arsenic  in  its  higher  state  of  oxidation  is 
not  detected  ;  the  difficulty  of  obtaining  copper  free  from  arsenic  ;  and 
that  its  results  are  interfered  with  by  the  presence  in  the  mixture  tested 
of  oxidizing  agents. 

Reinsch's  test  consists  in  acidulating  the  suspected  fluid  (urine)  with 
one-sixth  its  bulk  of  pure  hydrochloric  acid,  immersing  in  the  liquid  a 
strip  of  pure  electrotype  copper,  and  boiling.  If  arsenic  be  present,  a 
gray  or  bluish  deposit  will  form  upon  the  copper  ;  but,  as  such  a  deposit 
is  produced  by  other  substances  (bismuth,  antimony,  mercury)  as  well  as 
arsenic,  the  mere  formation  of  this  stain  is  not  evidence  of  the  presence 
of  an  arsenical  compound.  To  complete  the  test  the  copper  is  removed, 
washed,  and  dried  between  folds  of  filter  paper,  without  removing  the  de- 
posit. The  copper,  with  its  adhering  deposit,  is  then  rolled  into  a  little 
cylinder,  which  is  introduced  into  a  piece  of  Bohemian  tubing,  about  one- 
fourth  of  an  inch  in  diameter  and  six  inches  long.  The  tube  is  then 
held  at  an  angle  of  about  45°,  the  copper  coil  being  about  an  inch  and  a 
half  from  the  lower  end,  and  heated  at  the  point  where  the  copper  is.  If 
the  deposit  be  due  to  arsenic,  a  sublimate,  consisting  of  octahedral  crys- 
tals of  arsenic  trioxide,  will  form  at  some  point  in  the  upper,  cool  portion 
of  the  tube. 

Three  precautions  must  be  observed  by  the  physician  in  using  this 
test  :  1.  The  freedom  of  the  hydrochloric  acid  and  copper  from  arsenic 
must  be  demonstrated  by  a  blank  testing.  2.  No  stain  upon  the  copper 
is  evidence  of  the  presence  of  arsenic,  unless  it  yield  crystals  of  the  tri- 
oxide as  described.  3.  It  should  never  be  used  after  the  death  of  the 
patient,  especially  if  there  be  any  reason  to  believe  that  the  case  will  be 
the  subject  of  legal  proceedings. 

In  a  case  of  supposed  homicidal  poisoning  the  analyst  must  not 
confine  his  attention  to  any  one  poison,  however  directly  the  circum- 
stances of  the  case  may  point  to  the  use  of  this  or  that  toxic.  He  must 
so  conduct  the  analysis  as  to  be  enabled  to  predicate  the  absence  or 
presence  of  each  of  t^e  more  usually  employed  poisons.  For  this  reason 
a  systematic  course  of  analysis  must  be  followed,  in  which  the  search  for 
mineral  poisons,  phosphorus  excepted,  follows  that  of  those  of  an  organic 
nature.  This  arrangement  is  chosen,  firstly,  because  the  volatile  and 
some  of  the  alkaloidal  poisons,  being  subject  to  decomposition  in  contact 
with  putrefying  organic  material,  must  be  sought  for  at  the  earliest  pos- 
sible moment;  and  secondly,  because,  in  searching  for  mineral  poisons,  it 
is  necessary  to  destroy  all  organic  matter,  the  presence  of  which  would 
render  the  tests  applied  uncertain,  and  in  many  instances  delusive. 

The  best  method  of  accomplishing  this  destruction  of  organic  matter  is 
that  devised  by  Frezenius  and  von  Babo.  It  consists  in  oxidizing  the 
animal  or  vegetable  substances  by  a  mixture  of  hydrochloric  acid  and 
potassium  chlorate.  The  material  to  be  examined,  divided  into  small 


TOXICOLOGICAL    ANALYSIS.  129 

pieces  if  solid,  is  rendered  fluid  by  the  addition  of  water,  and,  after  the  ad- 
dition of  about  200  c.c.  of  hydrochloric  acid,  and  four  to  five  grams  of  potas- 
sium chlorate,  is  heated  over  the  water-bath,  small  quantities  of  chlorate 
being  added  from  time  to  time  until  the  mass  has  a  uniform  light  yellow 
color.  If  now  it  smell  strongly  of  chlorine,  it  is  warmed,  and  treated 
with  a  current  of  carbon  dioxide  until  the  chlorine  odor  has  disappeared, 
when  it  is  allowed  to  cool,  is  filtered,  and  the  residue  washed  with  hot 
water.  The  clear  filtrate  and  washings,  if  strongly  acid,  are  partially 
neutralized  by  the  addition  of  sodium  carbonate,  and  treated  with  a  cur- 
rent of  washed  hydrogen  sulphide,  the  gas  being  passed  through  the 
warmed  liquid  until,  after  shaking,  it  retains  a  strong  odor  of  sulphur- 
etted hydrogen.  The  vessel  is  then  corked  and  set  aside  until  the  fol- 
lowing day,  when  the  same  treatment  is  repeated,  as  again  on  a  third  day, 
a  long  contact  with  an  excess  of  hydrogen  sulphide  effecting  a  more  com- 
plete separati®n  of  the  metallic  sulphides  than  a  treatment  with  a  large 
volume  of  the  gas  during  a  shorter  period.  The  precipitate  formed  is 
now  collected  upon  a  filter,  and  washed  with  water  containing  a  small 
quantity  of  hydrogen  sulphide,  until  the  washings  do  not  give  the  faint- 
est cloudiness  when  boiled,  acidulated  with  nitric  acid,  and  tested  for 
chlorides  by  the  addition  of  silver  nitrate  solution. 

The  precipitate  is  then  treated  with  solution  of  ammonium  sulphy- 
drate,  which  effects  a  partial  separation  of  the  poisonous  metals,  some 
being  dissolved  and  others  remaining;  arsenic  trisulphide  will  pass  into  the 
solution.  This  is  now  evaporated  over  the  water-bath  to  dryness,  the 
residue  moistened  with  strong  nitric  acid  and  again  dried  over  the  water- 
bath,  the  treatment  with  nitrio  acid  being  repeated  two  or  three  times. 
To  the  residue  sodium  carbonate  and  sodium  nitrate  are  added,  and  the 
whole  heated  to  fusion  until  colorless.  It  is  then  allowed  to  cool,  and 
decomposed  by  the  addition  of  strong  sulphuric  acid  and  gradual  heating 
until  all  nitric  acid  is  expelled,  and  until  copious  white  fumes  are  given 
off.  The  residue  is  finally  dissolved  in  water,  and  if  there  be  any  cloudi- 
ness in  the  solution  (see  p.  132),  it  is  filtered  and  tested  for  arsenic  by  one 
of  the  following  methods: 

Of  all  the  tests  hitherto  devised  for  the  detection  of  arsenic,  the  most 
delicate  and  the  most  certain  is  that  originally  suggested  by  James  Marsh, 
in  1836,  and  subsequently  so  modified  by  Berzelius,  Otto,  and  others,  that 
but  little  of  the  original  method  remains  beyond  the  principles  upon 
which  it  is  based  (see  p.  117).  The  apparatus  consists  of  a  gener- 
ating flask  having  a  capacity  of  about  75  c.c.,  fitted  with  a  cork  through 
which  pass  a  funnel-tube,  drawn  out  and  turned  up  at  the  lower  end,  and 
a  tube  bent  to  a  right  angle  and  carrying  a  bulb  upon  its  horizontal 
limb.  This  tube  communicates  with  a  drying-tube,  filled  with  fragments 
of  calcium  chloride  enclosed  between  cotton  plugs,  and  this  in  turn  with 
a  piece  of  Bohemian  tubing,  about  an  eighth  of  an  inch  in  diameter  and 
about  two  feet  long,  whose  middle  third  is  coiled  in  a  spiral;  finally,  this 
Cube  is  connected  with  a  right-angle  tube,  whose  lower  extremity  dips 
into  a  solution  of  silver  nitrate. 

To  apply  the  test,  the  generating  flask  is  charged  with  pure  zinc, 
which  is  moistened  with  water  containing  a  few  drops  of  a  solution  of 
platinum  chloride  ;  the  solution  is  allowed  to  remain  upon  the  zinc  about 
ten  minutes,  and  is  then  washed  off.  The  apparatus  is  mounted  in  such  a 
\yay  that  all  its  joints  are  gas-tight,  and  sulphuric  acid,  diluted  with  a 
little  more  than  its  bulk  of  water  and  cooled,  is  poured  into  the  funnel- 
tube.  After  the  generation  of  hydrogen  has  continued  for  about  twenty 
9 


130  GENERAL    MEDICAL    CHEMISTRY. 

minutes,  the  coiled  portion  of  the  Bohemian  tube  is  heated  to  redness, 
and  the  heating  and  evolution  of  hydrogen  continued  for  a  full  half-hour. 
If  at  the  end  of  this  time  the  faintest  deposit  have  formed  in  the  cool  por- 
tion of  the  tube,  beyond  the  coil,  the  chemicals  are  to  be  rejected  as  im- 
pure, and  the  testing  is  to  be  repeated  with  others.  If  no  deposit  have 
formed,  the  suspected  liquid,  diluted  if  necessary  with  water,  is  slowly 
introduced  through  the  funnel-tube  in  such  a  way  that  no  air  is  carried 
down  with  it,  that  the  generating  flask  does  not  become  hot,  and  that  the 
introduction  of  the  entire  quantity  (which  should  not  measure  more  than 
two  or  three  fluid  ounces)  shall  require  from  an  hour  to  an  hour  and  a 
half.  If  the  proper  precautions  have  been  observed,  and  if  the  matters 
tested  contained  arsenic,  a  hair-brown  or  steel-gray  deposit  will  have 
formed  in  the  tube,  beyond  the  coil. 

As  Marsh's  test  is  usually  applied,  this  stain  may  be  produced  by  anti- 
mony as  well  as  by  arsenic j  but  if  the  method  indicated  above  have  been 
followed,  antimony,  if  present,  will  have  been  separated  at  an  earlier  stage 
of  the  process  (see  page  132). 

Some  toxicologists  direct  that  the  final  exit  of  the  gas  from  a  Marsh 
apparatus  be  from  a  drawn-out  end  of  the  tube,  pointing  upward,  and 
that  it  shall  be  there  ignited.  If,  under  these  conditions,  the  heating  of 
the  coil  be  discontinued,  in  the  presence  of  arsenic  a  white,  crystalline 
deposit  of  arsenic  trioxide  may  be  collected  upon  a  glass  surface  held 
above  the  flame,  or  a  brown  or  black  deposit  of  elementary  arsenic  upon 
a  cold,  white,  porcelain  surface  held  in  the  flame.  But  this  method — the 
original  form  of  Marsh's  test — is  attended  with  a  considerable  loss  of  arsenic, 
and  we  therefor  consider  it  preferable  to  collect  any  arsenic  which  may 
escape  deposition  in  the  tube  in  a  solution  of  silver  nitrate.  The  presence 
of  arsenic  in  the  silver  solution  may  be  subsequently  detected  by  cautiously 
floating  a  small  quantity  of  dilute  ammonium  hydrate  solution  upon  the 
surface  of  the  liquid,  when  a  yellow  cloudiness  is  observed  at  the  line  of 
contact. 

Owing  to  the  difficulty  formerly  experienced  in  obtaining  zinc  free  from 
arsenic,  it  was  suggested  that  nascent  hydrogen  be  obtained  by  the  de- 
composition of  acidulated  water  by  the  battery.  This  modification  of  the 
Marsh  process  is  usually  designated  as  Bloxam's  test,  as  its  use  was 
recommended  by  that  chemist  in  1860  ;  a  similar  apparatus  was,  however, 
suggested  by  Morton  previous  to  1847. 

If  a  determination  of  the  quantity  of  arsenic  present  be  required,  the 
sulphuric  acid  solution  obtained  as  directed  on  page  129  is  not  introduced 
directly  into  the  Marsh  apparatus,  but  is  treated  with  sulphur  dioxide, 
and  then,  after  boiling  until  the  excess  of  sulphur  dioxide  is  driven  off, 
with  hydrogen  sulphide.  Any  arsenic  present  is  thus  precipitated  as  the 
sulphide,  in  which  form  it  is  weighed,  with  the  precautions  indicated  in 
the  works  on  analytical  chemistry.  The  estimation  of  arsenic  as  uranium 
or  magnesium  pyroarsenate,  although  excellent  for  technical  purposes, 
is  not  available  for  the  small  quantities  which  the  toxicologist  has  usually 
to  deal  with.  The  method  by  weighing  the  deposit  formed  in  the  Marsh 
test,  recently  suggested  by  Gautier,  is  not  reliable. 

Another  test  is  that  suggested  by  Frezenius  and  von  Babo.  It  con- 
sists in  mixing  the  precipitate  of  sulphide,  obtained  as  above,  with  a 
mixture  of  potassium  cyanide  and  sodium  carbonate,  and  heating  in  a 
tube  through  which  passes  a  slow  current  of  carbon  dioxide.  If  arsenic 
be  present  it  will  appear  in  the  cool  part  of  the  tube  as  a  steel-gray  deposit. 

To  distinguish  between  an  arsenite  and  an  arsenate  in  solution,  ad- 


ANTIMONY.  131 

vantage  is  taken  of  the  colors  of  the  two  salts  of  silver.  To  the  faintly 
acid  solution  to  be  tested,  neutral  solution  of  silver  nitrate  is  added,  and 
the  mixture  then  rendered  neutral  by  blowing  upon  it  over  the  glass  stop- 
per of  a  bottle  moistened  with  ammonium  hydrate  solution.  If  an  arsenite 
be  present,  the  bright  yellow  silver  arsenite  is  formed;  and  if  an  arsenate, 
the  brick-red  silver  arsenate. 


ANTIMONY. 
Stibium Sb 122 

First  described,  about  the  middle  of  the  fifteenth  century,  by  Basil  Val- 
entine. Occurs  in  nature,  in  its  elementary  form,  in  small  quantity.  Its 
chief  ore,  which  was  known  to  the  ancients  as  crrt/x/xt,  o-rt/3t  and  stibium,  is 
the  trisulphide  (q.  v.). 

The  element  is  obtained  by  roasting  the  sulphide,  which  is  known  in 
commerce  as  black  antimony,  or  crude  antimony,  and  reducing  the  oxide 
so  obtained  by  heating  it  with  charcoal.  As  the  commercial  product, 
known  as  regulus  of  antimony,  is  always  contaminated  with  other  sub- 
stances, notably  with  arsenic,  it  is  necessary  to  purify  it  when  it  is  to  be 
used  for  medicinal  or  chemical  purposes.  This  purification  is  effected  by  fus- 
ing a  mixture  of  sixteen  parts  of  commercial  antimony,  one  part  of  the  na- 
tive trisulphide  of  antimony,  and  two  parts  of  dry  sodium  carbonate.  After 
cooling,  the  antimony  is  removed,  powdered,  and  again  fused  with  one  and 
one-half  part  of  sodium  carbonate  and  one  per  cent,  of  ferrous  sulphide; 
finally,  the  antimony  is  again  separated,  powdered,  and  fused  a  third  time 
with  one  part  of  sodium  carbonate  and  a  few  fragments  of  sodium  nitrate. 
Each  fusion  is  maintained  for  an  hour.  * 

Antimony  is  a  bluish  gray  solid,  having  a  brilliant  metallic  lustre, 
readily  crystallizable  by  fusion  and  cooling;  very  brittle  and  easily  pul- 
verized. Sp.  gr.  6.715.  It  is  tasteless  and  odorless,  rnelts  at  450°,  vola- 
tilizes at  a  bright  red  heat,  and  may  be  distilled  in  an  atmosphere  of 
hydrogen. 

In  its  chemical  properties  and  its  compounds,  antimony  resembles  ar- 
senic; it  is  not,  however,  as  readily  oxidized  as  that  element,  being  unal- 
tered by  exposure  to  air,  dry  or  moist,  at  ordinary  temperatures.  When 
sufficiently  heated  in  air  it  burns,  with  formation  of  the  trioxide,  as  a 
white,  crystalline  sublimate,  formerly  known  as  argentine  flowers  of 
antimony.  If  melted  antimony  be  dropped  from  a  height,  the  small 
globules,  exposing  a  large  surface  are  rapidly  oxidized,  and  in  their 
passage  through  the  air  are  followed  by  a  white  train  of  the  trioxide. 
Antimony  also  unites  directly  with  chlorine,  bromine,  iodine,  sulphur, 
and  with  many  metallic  elements.  Like  arsenic,  it  unites  indirectly  with 
hydrogen. 

Cold,  dilute  sulphuric  acid  is  without  action  on  antimony;  the  hot 
concentrated  acid  converts  it  into  antimonyl  sulphate,  while  sulphur  di- 
oxide is  given  off.  When  very  finely  divided,  antimony  is  dissolved  by 
hydrochloric  acid  under  the  influence  of  heat.  Nitric  acid  oxidizes  it 
readily  with  formation  of  antimonic  acid,  or  of  the  intermediate  oxide, 
Sb2O4.  It  is  readily  dissolved  by  aqua  regia,  with  which  it  forms  either 
the  trichloride,  SbCls,  or  the  pentachloride,  SbCl5.  It  is  not  dissolved  by 
solutions  of  the  alkaline  hydrates. 


132  GENERAL    MEDICAL    CHEMISTRY. 

The  element  itself  does  not  form  salts  with  the  oxacids.  There  are, 
however,  compounds  which  are  formed  by  the  substitution  of  the  group 
(SbO)',  an  univalent  radical,  for  the  basic  hydrogen  of  those  acids.  Simi- 
lar compounds  of  vanadium  and  of  arsenic  are  also  known  (see  Tartar 
Emetic,  p.  405). 

Antimony  is  also  capable  of  uniting  with  many  metals  to  form  alloys, 
some  of  which  are  definite,  crystalline  compounds. 

Antimony  is  largely  used  in  the  arts,  chiefly  in  the  form  of  alloys,  to 
which  it  communicates  hardness  and  the  property  of  expanding  at  the 
moment  of  solidification.  Its  principal  use  is  as  a  constituent  of  type- 
metal;  it  also  enters  into  the  composition  of  "Britannia  metal,"  "  Queen's 
metal,"  and  of  the  various  anti-friction  alloys  used  for  the  bearings  of 
machinery.  In  a  finely  divided  state  it  is  applied  to  papier  machu  and 
plaster  ornaments,  to  give  them  the  appearance  of  steel.  It  is  not  used 
in  medicine  in  its  elementary  form. 


Hydrogen  Antimonide. 

Antimoniuretted  hydrogen  —  Stibamine —  Stibonia  —  SbH3.  —  Does 
not  exist  in  nature,  and  has  not  as  yet  been  obtained  in  a  state  of  purity, 
being  always  mixed  with  a  large  quantity  of  hydrogen.  Its  composition, 
SbH3,  corresponding  to  that  of  the  hydrogen  compounds  of  the  other 
elements  of  this  group,  has  been  established  beyond  a  doubt  by  the  study 
of  its  products  of  substitution. 

It  is  a  gaseous  substance,  formed  from  reducible  compounds  of  anti- 
mony, under  the  same  conditions  which  govern  the  formation  of  hydrogen 
arsenide.  It  is  also  subject  to  decompositions,  similar  to  those  of  the 
arsenical  compound.  It  differs  from  hydrogen  arsenide  in  being  by  no 
means  as  poisonous,  and  in  its  action  upon  solutions  of  silver  nitrate. 
Hydrogen  arsenide,  when  passed  through  a  solution  of  the  silver  salt,  is 
decomposed  according  to  the  equation — 

6NO3Ag+AsH3+3HaO=6NO3H  +  AsO3H3+3Aga, 

elementary  silver  being  separated  as  a  black  powder,  while  arsenious 
acid  remains  in  the  solution,  from  which  the  yellow  silver  arsenite  may 
be  precipitated  by  cautiously  floating  dilute  ammonium  hydrate  upon  the 
surface  of  the  clear  liquid. 

In  the  case  of  hydrogen  antimonide,  a  black  deposit  is  also  formed,  but 
in  this  instance  it  is  not  elementary  silver,  but  silver  antimonide: 

3N03Ag+SbH8=3NO3H+SbAgs. 


Distinction  between  Arsenic  and  Antimony  by  Marsh's  Test. 

If  the  analysis  have  been  conducted  in  the  manner  indicated  upon 
p.  128,  any  antimony  present  is  separated  during  the  fusion  with  sodium 
nitrate  and  carbonate,  and  the  subsequent  solution  and  filtration,  as  an 
insoluble  white  powder,  from  which  the  element  may  be  obtained  by 
fusion  with  potassium  cyanide,  and  its  nature  determined  by  solution  in 


COMPOUNDS    OF    ANTIMONY    AND    OXYGEN. 


133 


aqua  regia,  which  solution  is  then  tested  for  antimony  (see  p.  138).  If, 
however,  Marsh's  test  be  applied  without  the  previous  steps  in  the  pro- 
cess, the  stain  of  arsenic  may  be  distinguished  from  that  of  antimony  by 
the  following  differences: 


The  Arsenical  Stain. 

First. — Is  farther  removed  from  the 
heated  portion  of  the  tube,  and,  if  small 
in  quantity,  is  double — the  first  hair- 
brown,  the  second  steel-gray. 

/Second. — Volatilizes  readily  when  heat- 
ed in  an  atmosphere  of  hydrogen,  being 
deposited  farther  along  in  the  tube  ;  the 
escaping  gas  has  the  odor  of  garlic. 

Third. — When  cautiously  heated  in  a 
current  of  oxygen,  brilliant  white  octahe- 
dral crystals  of  arsenic  trioxide  are  de- 
posited farther  along  in  the  tube. 

Fourth. — Instantly  soluble  in  solution 
of  sodium  hypochlorite. 

Fiftfi. — Slowly  dissolved  by  solution  of 
ammonium  sulphydrate;  more  rapidly 
when  warmed. 

Sixth. — The  solution  obtained  in  5° 
leaves,  on  evaporation  over  the  water-bath, 
a  bright  yellow  residue. 

Seventh. — The  residue  obtained  in  6° 
is  soluble  in  ;;qua  ammoniae,  but  insoluble 
in  hydrochloric  acid.  v  t 

Eighth. — Is  soluble  in  warm  nitric  acid ; 
the  solution  on  evaporation  yields  a  white 
residue,  which  turns  brick-red  when  moist- 
ened with  silver  nitrate  solution. 

Ninth.  —Is  not  dissolved  by  a  solution 
of  stannous  chloride. 


The  Antimonial  Stain. 

First. — Is  quite  near  the  heated  por- 
tion of  the  tube. 


Second. — Requires  a  much  higher  tem- 
perature for  its  volatilization ;  fuses  before 
volatilizing.  Escaping  gas  has  no  alliace- 
ous odor. 

Third. — No  crystals  formed  by  heating 
in  oxygen. 


Fourth. — Insoluble  in  solution  of  so- 
dium hypochlorite. 

Fifth. — Dissolves  quickly  in  solution  of 
ammonium  sulphydrate. 

Sixth. — The  solution  obtained  in  5° 
leaves,  on  evaporation  over  the  water-bath, 
an  orange-red  residue. 

Seventh. — The  residue  obtained  in  6° 
is  insoluble  in  aqua  ammoniae,  but  soluble 
in  hydrochloric  acid. 

Eighth. — Is  soluble  in  warm  nitric  acid ; 
the  solution  on  evaporation  yields  a  white 
residue,  which  is  not  colored  when  moist- 
ened with  silver  nitrate  solution. 

Ninth. — Dissolves  Blowly  in  solution  of 
stannous  chloride. 


When,  from  the  methods  followed,  it  is  doubtful  whether  the  stain  be 
antimonial  or  arsenical,  it  is  well  to  use  a  number  of  small  coils  of  heated 
tubing  (see  p.  129),  through  which  the  gas  is  made  to  pass  in  succession, 
rather  than  to  attempt  the  collection  of  stains  by  the  introduction  of 
porcelain  surfaces  into  the  flame  of  the  jet  ignited  as  it  issues  from  the 
end  of  the  tube,  as  by  the  latter  method  of  manipulation  much  of  the 
antimony  is  lost.  In  conducting  the  Marsh  test  for  antimony  the  pre- 
cautions mentioned  on  p.  130  are  to  be  observed. 


Compounds  of  Antimony  and  Oxygen. 

Three  compounds  of  these  elements  are  known: 

Antimony  trioxide Sb2O3. 

Antimony  pentoxide SbaO6. 

Intermediate  oxide Sb2O4. 

Antimony  trioxide — Antimonious  anhydride — Oxide  of  antimony — 
Antimonii  oxidum(U.  S.,  Br.)—Sb3O8— exists  in  nature,  and  is  worked 


134  GENERAL    MEDICAL    CHEMISTRY. 

as  an  ore  of  antimony  in  Algeria.  It  is,  however,  generally  prepared  arti- 
ficially for  use  in  the  arts  and  medicine,  by  decomposing  the  oxychloride 
(q.  v.).  This  decomposition  may  be  effected  in  a  variety  of  ways.  The 
best  method  of  obtaining  the  pure  oxide  consists  in  simply  heating  the 
oxychloride  strongly  in  a  crjupible,  when  it  is  decomposed  into  trioxide  and 
trichloride,  the  latter  being  volatilized.  The  United  States  Pharmacopoeia 
process  consists  in  first  obtaining  the  oxychloride,  which  is  then  decom- 
posed by  dilute  ammonium  hydrate  solution,  and  washing  to  separate 
the  ammonium  chloride  formed.  The  British  Pharmacopoeia  process  is 
similar,  but  the  decomposition  is  effected  by  a  solution  of  sodium  car- 
bonate, instead  of  by  ammonium  hydrate.  Antimony  trioxide  is  also 
formed  by  heating  antimony  in  a  current  of  air,  in  the  form  of  brilliant 
prismatic  crystals,  known  formerly  as  Flores  antimonii  argentei,  or  Nix 
stibii. 

As  prepared  by  the  wet  process,  it  is  an  amorphous,  tasteless,  and 
odorless  powder,  white  at  ordinary  temperatures,  but  turning  temporarily 
yellow  when  heated.  It  fuses  readily,  and,  if  protected  from  the  oxygen 
of  the  air,  volatilizes  and  condenses  in  the  form  of  prismatic  crystals.  If 
strongly  heated  in  contact  with  air,  it  burns  like  tinder,  and  is  converted 
into  the  intermediate  oxide,  Sb2O4.  It  is  insoluble  in  water. 

It  is  readily  reduced,  with  separation  of  elementary  antimony,  when 
heated  with  carbon  or  in  an  atmosphere  of  hydrogen.  It  is  also  readily 
oxidized,  as  when  brought  in  contact  with  nitric  acid,  or  with  solution  of 
potassium  permanganate.  It  dissolves  in  hydrochloric  acid,  with  forma- 
tion of  the  trichloride;  in  Nordhausen  sulphuric  acid,  from  which  solution 
there  separate  brilliant  crystalline  plates,  having*  the  composition  S2O7 
(SbO)a.  It  dissolves  readily  in  solution  of  tartaric  acid  or  of  hydropotas- 
sic  tartrate  (see  Tartar  Emetic).  By  boiling  solutions  of  the  alkaline  hy- 
drates it  is  gradually  converted  into  antimonic  acid. 

James'  Powder,  Pulvis  antimonialis  (Br.)  is  a  mixture  of  antimony 
trioxide  and  tricalcic  phosphate. 

Antimony  pentoxide — Antimonic  anhydride — Sb2O6 — is  obtained  by 
heating  metantimonic  acid  to  dull  redness.  It  is  an  amorphous,  tasteless, 
and  odorless  solid,  pale  lemon -yellow  when  cool,  and  becoming  tempora- 
rily darkened  when  heated.  When  heated  to  redness  it  gives  off  oxygen, 
and  the  intermediate  oxide  remains.  It  is  very  sparingly  soluble  in  water 
and  in  acids. 

Intermediate  oxide,  Sb?O4 — occurs  in  nature.  It  is  formed  when  the 
oxides  or  hydrates  of  antimony  are  strongly  heated,  or  when  the  lower 
stages  of  oxidation  or  the  sulphides  are  oxidized  by  nitric  acid,  or  by  fu- 
sion with  sodium  nitrate.  It  is  insoluble  in  water,  but  decomposed  by 
hydrochloric  acid,  hydropotassic  tartrate,  and  potash. 

The  constitution  of  this  compound  is  still  undetermined.  It  is  re- 
garded as  the  antimonic  salt  of  metantimonic  acid,  SbO3  (SbO)',  or  as  the 
anhydride  corresponding  to  an  acid  having  the  composition  Sb2O6H2.  The 
latter  view  is  probably  the  correct  one,  as  by  treatment  with  potash  it 
yields  a  compound  having  the  composition  Sb2OBK2,  which,  by  decompo- 
sition with  an  equivalent  quantity  of  sulphuric  acid,  yields  the  acid 
Sb2O5H9.  Moreover,  there  exists  in  nature  a  mineral  (romeine)  which  is 
the  calcium  salt  SbaO5Ca. 


CHLORIDES    OF    ANTIMONY.  135 


Antimony  Acids. 

The  normal  antimonous  acid,  SbO3H3,  corresponding  to  phosphorous 
acid,  is  not  known;  but  the  series  of  antimonic  acids  is  complete,  either 
in  the  form  of  salts  or  in  that  of  the  free  acid: 

Orthoantimonic  acid SbO4H3. 

Pyroantimonic  acid Sb2O7H4. 

Metantimonic  acid SbO3H. 

Besides  these  there  also  exists,  in  the  shape  of  its  sodium  salt,  a  de- 
rivative of  the  lacking  antimonous  acid: 

Metantimonous  acid . .  . .  SbO  H. 


But  little  practical  interest  attaches  to  these  acids,  or  to  their  salts. 
The  compound  sometimes  used  in  medicine  under  the  name  washed  dia- 
phoretic antimony  is  potassium  metantimonate,  united  with  an  excess  of 
antimony  pentoxide,  2SbO3K,  Sb2OB. 

The  hydropotassic  pyroantimonate,  Sb2O,KaH2,  6Aq,  is  a  valuable 
reagent  for  sodium,  with  which  it  forms  the  insoluble  sodium  salt.  The 
reagent  is  obtained  by  calcining  a  mixture  of  one  part  of  antimony  with 
four  parts  of  pota'ssium  nitrate,  fusing  the  product  with  its  own  weight 
of  potassium  carbonate,  and  dissolving  the  resulting  white  mass  in  water 
as  it  is  required  for  use. 


Chlorides  of  Antimony. 

Two  chlorides  and  several  oxychlorides  are  known: 

Antimony  trichloride — Protochloride  of  antimony — Butter  of  anti- 
mony— SbCla — is  obtained  by  passing  dry  chlorine  over  an  excess  of  an- 
timony or  of  antimony  trisulphide,  or  by  dissolving  the  trisulphide  in 
hydrochloric  acid,  or  by  distilling  together  mixtures,  either  of  antimony 
trisulphide  and  mercuric  chloride,  or  of  antimony  and  mercuric  chloride, 
or  of  antimonyl  pyrosulphate  and  sodium  chloride. 

At  low  temperatures  it  is  a  solid,  crystalline  body;  at  the  ordinary 
temperature,  a  yellow,  semi-solid  mass,  resembling  butter;  at  73.2°  it  melts 
to  a  yellow,  oily  liquid,  which  boils  at  223°. 

When  obtained  by  solution  of  the  trisulphide  in  hydrochloric  acid  of 
the  usual  strength,  it  forms  a  solution  with  the  water,  which,  concen- 
trated to  sp.  gr.  1.47,  is  the  Liq.  antimonii  chloridi  (U.  S.,  Br.),  used  as 
an  escharotic. 

The  trichloride  attracts  moisture  from  the  air  and  is  soluble  in  a  very 
small  quantity  of  water.  Upon  the  addition  of  a  larger  quantity  of  water, 
however,  the  chloride  is  decomposed,  and  a  white  powder  is  formed, 
which  was  formerly  known  as  powder  of  algaroth,  and  which  is  now  pre- 
pared as  a  step  in  the  manufacture  of  the  trioxide  and  of  tartar  emetic. 
The  composition  of  this  substance  varies  according  as  hot  or  cold  water 
is  used;  if  the  latter,  the  decomposition  is — 

SbCl3 + H3O = 2HC1 + SbOCl ; 


136  GENERAL    MEDICAL    CHEMISTRY, 

but  if  the  water  be  boiling — 

4SbCl3+5HaO=10HCl+Sb4O5Cla. 

In  water  which  contains  at  least  fifteen  per  cent,  of  hydrochloric 
acid,  antimony  trichloride  dissblves  wi^&out  the  formation  of  a  precipitate. 

Several  cases  of  poisoning  by  butter  of  antimony,  or  by  the  Liq. 
antimonii  chloridi,  are  upon  record,  the  substance  acting  both  locally 
as  a  corrosive  and  as  a  true  poison. 

It  is  used  in  the  bronzing  of  gun-barrels. 

Antimony  pentachloride,  SbCl5 — is  formed  by  the  action  of  chlorine 
in  excess  upon  antimony  or  antimony  trichloride,  and  distillation  in  a 
current  of  chlorine. 

It  is  a  fuming,  colorless  liquid,  which  solidifies  at  — 20°,  but  does  not 
melt  again  until  the  temperature  reaches  —6°.  It  absorbs  moisture  from 
the  air.  With  a  very  small  quantity  of  water,  and  by  evaporation  over 
sulphuric  acid,  it  forms  a  hydrate  having  the  composition  SbCl5,  4H2O, 
which  appears  in  the  form  of  transparent,  deliquescent  crystals.  With 
more  water  a  crystalline  oxychloride,  SbOCl3,  is  formed;  and  with  a  still 
larger  quantity,  a  white  precipitate  of  orthoantirnonic  acid,  SbO4H8,  is 
formed.  It  is  capable  of  uniting  with  other  chlorides  to  form  double 
compounds,  such  as  SbClB,  PC15. 

With  iodine,  bromine,  and  fluorine,  antimony  forms  compounds  similar 
in  composition  to  the  trichloride.  The  triiodide,  SbI3,  has  been  used  in 
medicine.  In  its  preparation  the  constituents  must  be  brought  together 
gradually  to  avoid  explosions. 

Sulphides  and  Oxysulphides  of  Antimony. 

Two  sulphides  of  antimony  and  a  number  of  ill-defined  oxysulphides 
are  known. 

Antimony  trisulphide — Black  antimony — Sulphuret  of  antimony — 
Antimonii  sulphuretitm  (U.  S.)  SbSs. — Occurs  in  nature,  and  is  the  chief 
ore  of  antimony;  it  is  also  formed  artificially  when  an  excess  of  hydrogen 
sulphide  is  passed  through  a  solution  of  tartar  emetic.  The  native  sul- 
phide is  in  the  form  of  steel-gray,  crystalline  masses;  the  artificial  pro- 
duct appears  as  an  orange-red  or  brownish  red,  amorphous  powder.  It  is 
met  with  in  commerce,  under  the  name  "  crude  antimony,"  in  conical 
loaves,  obtained  by  simple  fusion  of  the  native  sulphide  to  free  it  from 
gangue. 

It  is  soft,  readily  powdered,  quite  fusible,  and  has  a  brilliant  metallic 
lustre.  When  heated  in  contact  with  air  it  is  decomposed,  sulphur 
dioxide  is  given  off,  and  there  remains  a  brown,  vitreous,  more  'or  less 
transparent  mass,  composed  of  varying  proportions  of  oxide  and  oxysul- 
phides, known  as  crocus,  or  liver,  or  glass  of  antimony. 

An  oxysulphide  of  a  fine  red  color,  used  as  a  pigment  under  the  name 
antimony  cinnabar  or  antimony  vermilion,  is  obtained  by  the  action, 
under  the  influence  of  heat,  of  a  solution  of  sodium  hyposulphite  upon  a 
solution  of  antimony  trichloride,  or  of  tartar  emetic.  It  has  the  com- 
position Sb6S6O3. 

Antimony  trisulphide  is  an  anhydride,  corresponding  to  which  are 
salts  known  as  sulphantimonites,  having  the  general  formula  SbS3M'2H. 
If  an  excess  of  the  trisulphide  be  boiled  with  a  solution  of  hydrate  of 


ANTIMONIAL    POISONING.  137 

potassium,  or  of  sodium,  a  solution  is  obtained  containing  an  alkaline 
sulphantimonite  and  an  excess  of  antimony  trisulphide.  If  this  solution 
be  filtered  and  decomposed  while  still  hot,  an  orange-yellow  precipitate 
is  obtained,  which  is  the  antimonium  sulphuretum  (U.  S.,  Br.),  and  con- 
sists of  a  mixture,  in  varying  proportions,  of  the  trisulphide  and  the  tri- 
oxide.  If,  however,  the  solution  be  set  aside  and  allowed  to  cool,  a 
brown,  voluminous,  amorphous  precipitate  separates,  which  consists  of 
antimony  trisulphide,  antimony  trioxide,  potassium  or  sodium  sulphide, 
and  alkaline  sulphantimonite  in  varying  proportions,  and  which  is  known 
as  I£erme£  mineral,  antimonii  oxy  sulphuretum  (U.  S.).  If  now  the  solu- 
tion from  which  the  kermes  has  separated,  and  which  still  contains  an 
alkaline  sulphantimonite,  be  decomposed  with  sulphuric  acid,  a  reddish 
yellow  substance,  known  as  golden  sulphuret  of  antimony,  and  which  is  a 
mixture  of  tri-  and  pentasulphides,  separates. 

The  precipitate  obtained  when  hydrogen  sulphide  is  passed  through 
an  acid  solution  of  an  antimonial  compound  is,  according  to  circumstances, 
the  trisulphide  or  the  pentasulphide,  mixed  with  varying  quantities  of 
free  sulphur. 

By  the  action  of  hydrochloric  acid  upon  the  trisulphide,  hydrogen 
sulphide  is  liberated;  this  method  of  obtaining  that  gas  for  toxicological 
analysis,  formerly  resorted  to,  is  not  to  be  recommended.  In  such  anal- 
yses the  use  of  red  india-rubber  tubing  is  to  be  avoided,  as  it  owes  its 
color  to  a  sulphide  of  antimony. 

Antimony  pentasulphide — Antimonic  sulphide — Sb2S5 — is  obtained 
by  decomposing  an  alkaline  sulphantimonate'by  an  acid.  It  is  a  dark 
orange-red,  amorphous  powder,  readily  soluble  in  solutions  of  the  alkalies 
and  alkaline  sulphides,  the  solutions  containing  well-characterized  salts, 
called  sulphantimonates.  One  of  these,  sodium  sulphantirnonate,  SbS4 
Na3  +  9  Aq,  known  as  Schlippe's  salt,  forms  large,  yellow  crystals,  solu- 
ble in  water,  and  was  formerly  used  in  medicine. 


Antimonial  Poisoning1. 

The  compounds  of  antimony,  when  taken  internally,  are  poisonous, 
and  act  with  greater  or  less  energy  as  they  are  more  or  less  soluble. 
Their  poisonous  nature  was  early  recognized,  and  utilized  to  such  an  ex- 
tent that  in  1566  the  French  Parliament  found  it  necessary  to  prohibit 
their  use  in  medicine — a  prohibition  which  was  not  removed  until  a  cen- 
tury later. 

The  compound  which  is  now  the  most  frequent  cause  of  antimonial 
poisoning  is  tartar  emetic  (see  p.  405),  which  has  proved  fatal  in  a  dose 
of  one  and  one-half  grain,  although  recovery  has  followed  the  ingestion 
of  doses  as  large  as  half  an  ounce  in  several  instances.  Indeed,  when  large 
doses  are  taken,  the  chances  of  recovery  seem  to  be  better  than  after  small 
doses,  probably  owing  to  the  fact  that  in  the  former  instance  the  poison  is 
more  quickly  and  more  completely  discharged  by  vomiting.  When  ad- 
ministered with  murderous  intent,  antimonials  are  sometimes  given  in  small 
and  often  repeated  doses,  the  victim  finally  dying  of  exhaustion.  When 
the  existence  of  such  a  case  is  suspected,  the  urine  should  be  examined. 

The  treatment  in  acute  antimonial  poisoning  should  consist,  first,  in 
inducing  vomiting,  if  it  have  not  already  occurred,  by  the  administration 
of  hot  water;  should  this  fail  to  act,  the  contents  of  the  stomach  are  to  be 
removed  by  the  stomach-pump.  When  this  has  been  done,  tannin  in 


138  GENERAL    MEDICAL    CHEMISTRY. 

some  form,  decoction  of  oak-bark,  cinchona,  nutgalls,  strong  tea,  should 
be  given,  with  a  view  to  the  conversion  of  any  remaining  poison  into  an 
insoluble  compound. 

The  presence  of  antimony  in  the  viscera  is  best  detected  by  Marsh's 
test  (see  p.  132). 

It  must  not  be  forgotten  that  antimony  is  very  liable  to  contamina- 
tion with  arsenic,  which,  from  defective  manipulations,  may  find  its  way 
into  the  medicinal  antimouials. 


Analytical  Reactions. 

Besides  the  reactions  of  Marsh's  test,  the  presence  of  antimony  may 
be  detected  by  the  following:  1st,  the  formation  of  an  orange-red  pre- 
cipitate when  hydrogen  sulphide  is  passed  through  an  acid  solution,  the 
precipitate  being  soluble  in  ammonium  sulphydrate  and  in  hot  hydro- 
chloric acid;  2d,  the  formation  of  a  bluish,  metallic  deposit  upon  copper 
immersed  in  a  boiling  solution,  acidulated  with  hydrochloric  acid — the 
stain,  when  heated  in  a  tube  open  at  both  ends,  yielding  an  amorphous 
white  sublimate  (Reinsh's  test). 

The  determination  of  the  quantity  of  antimony  is  difficult  and  re- 
quires great  care;  it  should  be  converted  into  the  oxide,  Sb3O4,  and 
weighed  as  such.  Processes  based  upon  the  formation  and  weighing  of 
the  sulphide  are  apt  to  lead  to  fallacious  results. 


BOKIC    ACIDS.  139 


IV.  BORON  GROUP. 

BORON. 
B 11 

This  element  forms  a  group  by  itself,  none  other  being  known  which 
resembles  it  in  its  chemical  properties.  It  is  trivalent  in  all  of  its  com- 
pounds. It  forms  but  one  oxide,  which  is  the  anhydride  of  a  tribasic 
acid.  It  forms  no  compound  with  hydrogen. 

Boron  does  not  exist  as  such  in  nature,  but  occurs  in  combination  as 
boracic  acid  and  the  borates  of  calcium,  magnesium,  and  sodium.  It  was 
isolated  almost  simultaneously  by  Davy,  Gay-Lussac,  and  Thenard.  It 
may  be  obtained  in  two  allotropic  forms — amorphous  and  crystalline. 

Amorphous  boron  is  obtained  by  the  decomposition  of  its  oxide  by 
metallic  sodium  or  potassium.  It  is  a  greenish  brown  powder;  sparingly 
soluble  in  water,  infusible;  it  unites  directly  with  chlorine,  bromine, 
oxygen,  sulphur,  and  nitrogen. 

Crystallized  boron  is  formed  when  the  oxide,  chloride,  or  fluoride  is 
reduced  by  aluminium;  or  when  the  amorphous  variety  is  heated  with 
aluminium  to  a  high  temperature,  without  contact  of  air.  The  product 
varies  in  color  from  a  deep  garnet  red  to  a  faint,  almost  colorless,  yel- 
low. The  crystals  are  quadratic  prisms,  more  or  less  transparent  as 
they  are  lighter  or  darker  in  color;  very  hard  and  capable  of  refracting 
light  strongly;  sp.  gr.,  2.GS.  When  strongly  heated  in  oxygen,  it  first 
swells  up,  and  finally  burns  at  a  high  temperature.  It  generally  contains 
small  quantities  of  carbon  and  aluminium.  Like  amorphous  boron,  it  burns 
readily  in  an  atmosphere  of  chlorine.  It  also  has  a  marked  tendency  to 
combine  with  nitrogen,  being  capable,  at  elevated  temperatures,  of  de- 
composing ammonia,  from  which  it  removes  the  nitrogen,  to  form  the 
nitride,  BN,  while  hydrogen  is  liberated.  It  is  not  dissolved  by  any  acid. 
It  forms  an  alloy,  or  compound,  with  platinum,  which  is  much  more  fusi- 
ble than  is  that  metal. 


Boron  Trioxide. 

JBoric  anhydride — Boracic  anhydride — B2O3. — This,  the  only  com- 
pound of  boron  with  oxygen,  is  obtained  by  heating  boric  acid  to  redness 
in  a  platinum  vessel  until  all  water  is  driven  off.  The  oxide  remains  on 
cooling  as  a  transparent,  glass-like  mass,  which  is  used  to  a  limited  ex- 
tent in  blowpipe  analysis. 


Boric  Acids. 

Quite  a  number  of  acids  of  boron  have  been  described,  either  free  or 
as  salts,  all  of  which  are  hydrates  of  the  trioxide,  and  all  derivable  from 
the  tribasic  or  orthoboric  acid,  by  loss  of  the  elements  of  water.  Of  these 
the  most  important  are  ortho-,  meta-,  and  tetraboric,  or  pyroboric,  acids. 


140  GENERAL    MEDICAL    CHEMISTKY. 

Orthoboric  acid — Boracic  acid — Boric  acid — B03H8 — exists  in  nature 
in  volcanic  regions,  notably  in  Tuscany.  In  this  region,  formerly  the  main 
source  of  supply  of  boracic  acid  and  of  borax,  jets  of  steam,  known  as 
suffioni,  escape  through  fissures  in  the  earth  on  the  hillsides.  Over  these 
are  built  a  series  of  shallow-basins,  through  which  the  vapors  are  made  to 
pass,  and  from  one  to  another  of  winch  water  passes  slowly  by  gravity, 
and  in  its  course  becomes  charged  with  boracic  acid,  which  is  then  con- 
verted into  borax. 

To  obtain  the  acid,  a  boiling,  concentrated  solution  of  borax  is  slowly 
decomposed  with  an  excess  of  sulphuric  acid;  on  cooling  the  acid  crystal- 
lizes out. 

Orthoboric  acid  is  in  the  form  of  brilliant,  crystalline  plates,  unctuous  to 
the  touch;  odorless;  slightly  bitter;  soluble  in  twenty-five  parts  of  water  at 
10°;  soluble  in  alcohol,  the  alcoholic  solution  burning  with  a  green  flame. 
If  an  aqueous  solution  of  boric  acid  be  distilled,  a  portion  of  the  acid  is 
carried  over  with  the  aqueous  vapors.  Its  solution  exhibits  an  acid  reac- 
tion with  litmus  paper,  yet  it  turns  turmeric  paper  brown,  a  change  of 
color  produced  by  the  alkalies. 

If  orthoboric  acid  be  heated  for  some  time  at  80°,  it  loses  the  elements 
of  a  molecule  of  water,  and  is  converted  into  metaboric  acid,  BOaH: 

B08HS=H30+B08H. 

If,  however,  it  be  heated  to  about  100°  for  about  eight  days,  four  mole- 
cules unite  with  loss  of  five  molecules  of  water: 

4BO,H8=5HaO+B407Ha. 

Tetraboric  acid  or  Pyroboric  acid,  B4O7H2 — is  a  substance  of  little  in- 
terest in  itself,  but  whose  sodium  salt  is  the  most  important  compound  of 
boron.  Another  tetraboric  acid,  B4O9H6,  has  also  been  described. 


Compounds  of  Boron  with  Elements  of  the  Chlorine  Group. 

The  fluoride,  bromide,  and  chloride  have  been  described. 

Boron  fluoride,  BF3 — is  prepared  by  heating  together  boron  trioxide, 
fluor-spar,  and  sulphuric  acid.  It  is  a  colorless  gas;  fuming  when  exposed 
to  the  air;  very  soluble  in  water,  with  which  it  enters  into  combination,  a 
part  of  the  boron  separating  as  boron  trioxide,  while  an  acid  liquid  re- 
mains, which  contains  hydrofluoboric  acid,  BF4H.  The  fluoride  is  not 
decomposed  at  a  red  heat,  but  is  by  the  alkaline  metals  in  excess,  with  for- 
mation of  an  alkaline  fluoride  and  elementary  boron.  It  carbonizes  or- 
ganic matter,  as  does  sulphuric  acid. 

Boron  chloride,  BC13 — is  obtained  by  heating  dry  amorphous  boron  in 
a  current  of  chlorine,  and  passing  the  vapors  into  a  well-cooled  receiver. 
It  is  a  colorless,  mobile  liquid;  boils  at  17°;  sp.  gr.  1.35.  It  is  capable  of 
uniting  with  ammonia  to  form  a  crystalline  compound.  It  is  completely 
decomposed  by  water,  with  formation  of  orthoboric  and  hydrochloric  acids. 

Boron  bromide,  BBr3. — Formed  by  the  action  of  vapor  of  bromine 
upon  a  mixture  of  boron  trioxide  and  charcoal  heated  to  redness.  A  thick, 
colorless  liquid;  boils  at  90°;  sp.  gr.  2.69. 


CAKB01N".  1-il 


Y.  CARBON  GROUP. 

CARBON C 12 

SILICON Si 28 

The  two  elements  composing-  this  group  are  of  great  interest,  and  are 
closely  related  to  each  other  by  resemblances  in  their  chemical  and  physi- 
cal properties.  They  are  both  quadrivalent,  and  form  hydrogen  com- 
pounds in  which  one  atom  of  carbon  or  silicon  is  combined  with  four 
atoms  of  hydrogen.  The  saturated  oxide  of  each  is  the  anhydride  of  a 
dibasic  acid.  They  are  both  solid  and  combustible,  and  each  occurs  in 
three  distinct  allotropic  conditions,  one  amorphous,  one  graphitoid,  and 
one  crystalline.  The  resemblances  existing  between  their  compounds  are 
close,  so  far  as  they  go.  But  the  compounds  of  silicon  with  which  we 
are  acquainted  are  by  no  means  as  numerous  as  those  of  carbon,  although 
the  recent  researches  of  Friedei  would  indicate  that,  in  this  respect  also, 
the  relationship  between  the  two  elements  will  be  found  to  be  close. 

In  the  following  table  the  analogies  between  some  of  the  compounds 
of  the  two  elements  are  shown  : 

CH  — CO— COa  —  CO3H2  — CC14  — CHC13  —  CHI3  — C2CL  — CS2. 
SiH4— -          SiOa— SiO8H2— SiCl4— SiHCls— SiHI3— SiaCl6— SiSa. 


CARBON. 
C 12 

An  element  known  from  remote  antiquity  in  all  its  three  allotropic 
forms,  whose  chemical  identity  and  elementary  nature  were,  however, 
first  recognized  by  Lavoisier.  It  occurs  in  nature  in  all  of  its  elementary 
forms,  and  in  combination  in  the  three  kingdoms  of  nature,  it  being  the 
element  especially  characteristic  of  such  substances  as  exist  only  in  ani- 
lal  and  vegetable  bodies. 

Its  three  allotropic  forms  differ  from  each  other  widely  in  appearance 
and  in  other  physical  properties;  they  occur  in  nature  as  :  1st,  diamond  ; 
2d,  graphite;  3d,  coal. 

Diamond. — Occurs  in  nature  in  octahedral  crystals,  in  India,  Brazil, 
Australia,  and  South  Africa.  It  has  also  been  found  in  North  Carolina 
and  in  Georgia,  in  alluvial  sand,  clay,  sandstone,  or  conglomerate.  There 
remains  little  doubt  that  diamonds  have  also  been  obtained  artificially, 
but,  owing  to  our  inability  to  cause  the  formation  to  take  place  under 
proper  physical  conditions,  or  to  their  too  rapid  formation,  diamonds  of 
very  small  size  only  have  been  thus  far  obtained. 

Diamonds  are  usually  colorless  or  slightly  yellowish,  sometimes  yel- 
low, blue,  green,  pink,  brown,  or  black.  The  more  faintly  colored  are 
transparent  and  have  a  brilliant  lustre  or  fire,  which  is  enhanced  by  the 
operation  of  cutting  and  polishing,  which  consists  in  multiplying  the  num- 


142  GENERAL    MEDICAL    CHEMISTRY. 

ber  of  facets,  or  surfaces,  of  the  stone,  by  holding  it,  suitably  supported, 
in  contact  with  a  quickly  revolving  metal  plate,  coated  with  oil  and  dia- 
mond dust. 

The  diamond  refracts  light  to  a  greater  degree  than  any  other  trans- 
parent solid,  and  it  is  chiefly  to  this  property  that  its  great  brilliancy  is 
due.  Its  index  of  refraction  is  2.47/to  2.75. 

It  is  the  hardest  known  substance,  the  solid  approaching  it  most 
nearly  in  this  respect  being  crystallized  boron.  It  is  very  brittle,  a  bad 
conductor  of  heat  and  of  electricity  ;  sp.  gr.  3.50  to  3.55.  When  very 
strongly  heated  in  vacuo  it  swells  up,  leaving  a  black  mass  resembling 
coke;  if  heated  in  oxygen  it  ignites  and  unites  with  the  oxygen  to  form 
carbon  dioxide. 

Diamonds,  whose  size,  color,  or  imperfections  render  them  unfit  for 
purposes  of  luxury,  are  known  as  bort,  and  are  used,  either  whole  or  pow- 
dered, for  a  variety  of  purposes  in  the  arts  where  great  hardness  is 
required,  as  in  the  polishing,  drilling,  etc.,  of  diamonds  arid  other  hard 
stones,  in  dressing  millstones,  in  cutting  glass,  etc. 

In  weighing  diamonds  a  special  arbitrary  unit,  called  the  carat,  is 
used,  which  is  equivalent  to  four  troy  grains,  or  about  0.25  gram.  In 
the  cutting  a  diamond  loses  two-thirds  or  more  of  its  weight.  The 
largest  cut  diamond  known  is  the  Orloff,  belonging  to  the  Emperor  of 
Russia,  which  weighs  one  hundred  and  ninety-five  carats  (one  and  five- 
eighths  ounce) ;  it  is  said  to  have  weighed  before  cutting  seven  hundred 
and  seventy-nine  carats,  or  nearly  six  and  one-half  ounces. 

The  diamond  is  almost  pure  carbon,  containing  a  mere  trace  of  silex 
and  ferric  oxide. 

Graphite. — A  variety  of  carbon,  almost  as  free  from  foreign  admix- 
ture as  is  the  diamond,  and  like  it,  occurring  in  the  crystalline  form,  yet 
widely  differing  from  it  in  its  physical  properties. 

It  is  soft  enough  to  be  scratched  by  the  nail;  crystallizes  in  hexagonal 
plates;  is  opaque  and  of  a  dark  gray  color,  is  greasy  to  the  touch,  and 
stains  any  light-colored  substance  upon  which  it  is  rubbed;  is  a  good 
conductor  of  electricity,  and  a  better  conductor  of  heat  than  the  diamond. 
It  contains  from  one  to  two  per  cent,  of  impurities. 

Graphite  has  been  obtained  artificially.  Molten  cast-iron  dissolves 
carbon  to  a  limited  extent,  and,  if  it  be  allowed  to  cool  slowly,  the  carbon 
separates  in  the  form  of  crystals,  identical  in  appearance  and  properties 
with  those  of  native  graphite.  These  crystals  may  be  separated  from  the 
iron  by  dissolving  the  latter  in  hydrochloric  acid. 

Graphite  is  extensively  mined  in  England,  Siberia,  and  the  United 
States,  and  is  used  in  the  arts,  under  the  names  black  lead  and  plumbago, 
in  the  manufacture  of  pencils,  crucibles,  stove-polish,  etc.,  and  in  electro- 
typing. 

Amorphous  carbon  exists  in  nature  in  enormous  deposits,  the  re- 
mains of  vegetable  life  of  past  ages,  in  the  form  of  the  different  varieties 
of  coal,  which  contain  from  eight  to  twenty-five  per  cent,  of  substances 
other  than  carbon.  Anthracite  coal  is  hard  and  dense;  it  does  not  flame 
when  burning;  is  difficult  to  kindle,  but  gives  great  heat  with  a  suitable 
draught.  It  contains  eighty  to  ninety  per  cent,  of  carbon,  and  is  some- 
times known  as  stone-coal.  jBituminous  coal  varies  greatly  in  appear- 
ance, and  differs  from  anthracite  in  that,  when  burning,  it  gives  off  gases 
which  produce  a  flame.  Some  varieties  are  quite  soft,  while  others,  such 
as  jet,  which  is  a  kind  of  lignite,  are  hard  enough  to  assume  a  high  pol- 
ish. It  is  usually  compact  in  texture,  and  very  frequently  contains  im- 


CAEBOJS".  143 

pressions  of  leaves,  fruits,  and  other  parts  of  vegetables.  It  contains 
about  seventy-five  per  cent,  of  carbon. 

Besides  these  forms  in  which  carbon  occurs  in  nature,  it  is  artificially 
prepared  for  use  in  the  arts,  by  the  decomposition  of  substances  rich  in 
carbon.  The  kinds  of  artificial  coal  differ  from  each  other  according  to 
the  different  composition  of  the  substances  in  whose  decomposition  they 
have  their  origin.  Ordinary,  or  vegetable  charcoal,  is  obtained  by  burn- 
ing woody  fibre  with  an  insufficient  supply  of  air,  either  incidentally  in 
the  distillation  of  wood,  or  as  a  separate  industry.  It  is  brittle  and  so- 
norous; has  the  form  of  the  wood  from  which  it  was  obtained,  and  retains 
all  the  mineral  matter  present  in  the  woody  tissue.  Its  specific  gravity 
is  about  1.57.  It  has  the  power  of  condensing  within  its  pores  odorous 
substances  and  large  quantities  of  gases:  90  volumes  of  ammonia,  55  of 
hydrogen  sulphide,  9.25  of  oxygen.  This  property  is  taken  advantage 
of  in  a  variety  of  ways.  Its  power  of  absorbing  odorous  bodies  ren- 
ders it  valuable  as  a  disinfecting  and  filtering  agent,  and  in  the  pre- 
vention of  putrefaction  and  fermentation  of  certain  liquids.  It  is  with 
this  view  that  the  interiors  of  barrels  intended  to  hold  wine,  beer,  or 
water,  are  carbonized.  Certain  odorous  culinary  operations  are  rendered 
inodorous  by  the  introduction  of  a  fragment  of  charcoal  into  the  pot. 
The  efficacy  of  charcoal  as  a  filtering  material  is  due  also,  in  a  great 
measure,  to  the  oxidizing  action  of  the  oxygen  condensed  in  its  pores;  in- 
deed, if  charcoal  be  boiled  with  dilute  hydrochloric  acid,  dried,  and  heated 
to  redness,  the  oxidizing  action  of  the  oxygen,  which  it  thus  condenses, 
is  very  energetic.  , 

Lamp-black  is  obtained  by  incomplete  combustion  of  some  resinous 
or  tarry  substance,  the  smoke  or  soot  from  which  is  directed  into  suitable 
condensing-chambers.  It  is  a  light,  amorphous  powder,  and  contains  a 
notable  quantity  of  oily  and  tarry  material,  from  which  it  may  be  freed 
by  heating  in  a  covered  vessel.  It  is  used  in  the  manufacture  of  printer's 
ink. 

Coke  is  the  substance  remaining  in  gas-retorts  after  the  distillation  of 
bituminous  coal  in  the  manufacture  of  illurninating-gas.  As  all  sub- 
stances capable  of  yielding  gases  when  heated  have  been  driven  off,  coke 
does  not  possess  the  property  of  flaming  when  burned.  It  is  a  hard,  gray- 
ish substance,  usually  very  porous,  dense,  and  sonorous.  When  iron  re- 
torts are  used,  a  portion  of  the  gaseous  products  are  decomposed  by  con- 
tact with  the  hot  iron  surface,  upon  which  there  is  then  deposited  a  layer 
of  very  hard,  compact,  grayish  carbon,  which  is  a  good  conductor  of  elec- 
tricity, and  furnishes  the  best  material  for  making  the  carbons  of  galvanic 
batteries  and  the  points  for  the  electric  light.  It  does  not  .form  when 
gas  is  made  in  clay  retorts. 

Animal  charcoal  is  obtained  by  calcining  animal  matters  in  closed  ves- 
sels; if  prepared  from  bones  it  is  known  as  bone-black;  if  from  ivory,  ivory- 
black  ;  the  latter  is  used  as  a  pigment,  the  former  as  a  decolorizing  agent. 
Bones  yield  about  sixty  per  cent,  of  bone-black,  which  contains,  besides 
carbon,  nitrogen  and  the  phosphates,  and  other  mineral  substances  of  the 
bones.  It  possesses  in  a  remarkable  degree  the  power  of  absorbing 
coloring  matters,  for  which  purpose  it  is  largely  used  in  sugar-refining. 
When  its  decolorizing  power  is  lost  by  saturation  with  pigmentary  bodies, 
it  may  be  restored,  although  not  completely,  by  calcination.  For  certain 
purposes  in  the  laboratory  purified  animal  charcoal,  i.  e.,  freed  from  min- 
eral matter,  is  required,  and  is  obtained  by  extracting  the  commercial 
article  with  hydrochloric  acid  and  washing  it  thoroughly;  its  decolorizing 


144  GEXEEAL    MEDICAL    CHEMISTRY. 

power  is  diminished  by  this  treatment.  Animal  charcoal  has  the  power 
of  removing  from  a  solution  certain  crystalline  substances,  notably  the 
alkaloids,  and  a  method  has  been  suggested  for  separating  these  bodies 
from  organic  mixtures  by  its  use. 

The  most  notable  chemical  property  of  carbon  is  the  readiness  with 
which  it  unites  with  oxygen  'at  high,  temperatures  —  a  property  of  the  ele- 
ment not  only  in  its  three  simple  forms,  but  also  in  most  of  its  com- 
pounds. The  product  of  the  union  is  carbon  dioxide,  if  the  supply  of 
oxygen  is  sufficient;  if  oxygen  be  present  in  more  limited  quantity,  carbon 
monoxide  is  formed. 

The  affinity  of  carbon  for  oxygen  renders  it  a  most  valuable  reducing 
agent.  Many  oxides,  when  heated  with  charcoal,  are  reduced  with  for- 
mation of  carbon  dioxide: 

2CuO  +     C     =     2Cu     +     CO2 

Cupric  Carbon.  Copper.  Carbon 

oxide.  dioxide. 

The  reducing  power  of  oxygen  is  utilized  in  many  processes  in  the 
arts,  as  in  the  working  of  iron  and  other  ores. 

If  a  current  of  steam  be  passed  over  strongly  heated  coke,  the  watery 
vapor  is  reduced,  hydrogen  and  carbon  monoxide  being  formed  — 


a  reaction  utilized  in  the  manufacture  of  an  illuminating  gas,  known  as 
water-gas. 

At  elevated  temperatures,  about   1000°,  carbon  also  unites  directly 
with  sulphur  to  form  a  volatile  liquid  —  carbon  disulphide. 


COMPOUNDS    OF    CAKBON. 


145 


COMPOUNDS  OF  CARBON. 

Organic  Substances. 

In  the  seventeenth  and  eighteenth  centuries,  chemists  had  observed 
that  there  might  be  extracted  from  animal  and  vegetable  bodies  substances 
which  differed  much  in  their  properties  from  those  which  could  be  ob- 
tained from  the  mineral  world;  substances  which  burned  without  leav- 
ing a  residue,  and  many  of  which  were  subject  to  the  peculiar  changes 
wrought  by  the  processes  of  fermentation  and  putrefaction.  It  was  not 
until  the  beginning  of  the  present  century,  however,  that  chemistry  was 
divided  into  the  two  sections  of  inorganic  and  organic. 

In  the  latter  class  were  included  all  such  substances  as  existed  only  in 
the  organized  bodies  of  animals  and  vegetables,  -and  which  seemed  to  be 
of  a  different  essence  from  that  of  mineral  bodies,  as  chemists  had  been 
unable  to  produce  any  of  these  organic  substances  by  artificial  means. 
Later  in  the  history  of  the  science  it  was  found  that  these  bodies  were  all 
made  up  of  a  very  few  elements,  and  that  they  all  contained  carbon. 
Gmelin  at  this  time  proposed  to  consider  as  organic  substances  all  such  as 
contained  more  than  one  atom  of  carbon,  his  object  in  thus  limiting  the 
minimum  number  of  atoms  of  carbon  being  that  substances  containing  one 
atom  of  carbon,  such  as  carbonic  acid  and  marsh-gas,  were  formed  in  the 
mineral  kingdom,  and  consequently,  according  to  then  existing  views, 
could  not  be  considered  as  organic.  Illogical  as  such  a  distinction  is,  we 
find  it  still  adhered  to  in  text-books  of  very  recent  date. 

The  notion  that  organic  substances  could  only  be  formed  by  some  mys- 
terious agency,  existing  only  in  organized  beings,  was  finally  exploded  by 
the  labors  of  Wohler  arid  Kolbe.  The  former  obtained  urea  from  ammo- 
nium cyanate;  while  the  latter,  at  a  subsequent  period,  formed  acetic 
acid,  using  in  its  preparation  only  such  unmistakably  mineral  substances 
as  coal,  sulphur,  aqua  regia,  and  water. 

During  the  half-century  following  Wohler's  first  synthesis,  chemists 
have  succeeded  not  only  in  making  from  mineral  materials  many  of  the 
substances  previously  only  formed  in  the  laboratory  of  nature,  but  have 
also  produced  a  vast  number  of  carbon  compounds  which  were  previously 
unknown,  and  which,  so  far  as  we  know,  have  no  existence  in  nature.  At 
the  present  time,  therefor,  we  must  consider  as  an  organic  substance  any 
compound  containing  carbon,  whatever  may  be  its  origin  and  whatever  its 
properties.  Indeed,  the  name  organic  is  retained  merely  as  a  matter  of 
convenience,  and  not  in  any  wav  as  indicating  the  origin  of  these  com- 
pounds. Although,  owing  to  the  great  number  of  the  carbon  compounds, 
it  is  still  convenient  to  treat  of  them  as  forming  a  section  by  themselves, 
their  relations  with  the  compounds  of  other  elements  is  frequently  very 
close;  indeed,  within  the  past  few  years,  compounds  of  silicon  have  been 
obtained,  which  indicate  the  possibility  that  that  element  is  capable  of 
forming  series  of  compounds  as  interesting  in  numbers  and  variety  as 
those  of  carbon. 

Nevertheless,  there  are  certain  peculiarities  exhibited  by  carbon  in  its 
compounds,  which  are  not  possessed  to  a  like  extent  by  any  other  element, 
10 


146  GENERAL   MEDICAL    CHEMISTRY. 

and  which  render  the  study  of  organic  substances  peculiarly  interesting 
and  profitable. 

In  the  study  of  the  compounds  of  the  other  elements,  we  have  to  deal 
with  a  small  number  of  substances,  relatively  speaking,  formed  by  the 
union  with  each  other  of  a  large  number  of  elements.  With  the  organic 
substances  the  reverse  is  the  case;  fbr,  although  compounds  have  been 
formed  which  contain  carbon  along  with  each  of  the  other  elements,  the 
great  majority  of  the  organic  substances  are  made  up  of  carbon,  combined 
with  a  very  few  other  elements,  hydrogen,  oxygen,  an,d  nitrogen  occurring 
in  them  most  frequently. 

It  is  chiefly  in  the  study  of  the  carbon  compounds  that  we  have  to  deal 
with  radicals  (see  p.  17).  Among  mineral  substances  there  are  many 
whose  molecules  consist  simply  of  a  combination  of  two  atoms;  among 
organic  substances  there  is  none  which  does  not  contain  a  radical;  indeed, 
organic  chemistry  has  been  defined  as  "the  chemistry  of  compound 
radicals." 

The  atoms  of  carbon  possess  in  a  higher  degree  than  those  of  any  other 
element,  silicon  possibly  excepted,  the  power  of  uniting  with  each  other, 
and  in  so  doing  of  interchanging  valences.  Were  it  not  for  this  property 
of  the  carbon  atoms,  we  could  have  but  one  saturated  compound  of  carbon 
and  hydrogen,  CH4,  or,  expressed  graphically: 

H 

H— C— H. 


There  exists,  however,  a  great  number  of  such  compounds,  which  differ 
from  each  other  by  one  atom  of  carbon  and  two  atoms  of  hydrogen.  In 
these  substances  the  atoms  of  carbon  may  be  considered  as  linked  together 
in  a  continuous  chain,  their  free  valences  being  satisfied  by  atoms  of  hy- 
drogen; thus: 


H  H    H  H    H    H    H 

H— C— H  H— C— C— H  H— C— C— C—  C— H 

I  II  I      I      I      I 

H  H    H  H    H    H    H 


If  now  one  atom  of  hydrogen  be  removed  from  either  of  these  combina- 
tions, we  have  a  group  possessing  one  free  valence,  and  consequently 
univalent.  The  decompositions  of  these  substances  show  that  they  con- 
tain such  radicals,  and  that  their  typical  formulae  are: 


HOMOLOGOUS  SERIES. 

It  will  be  observed  that  these  formulas  differ  from  each  other  by  CH2, 
or  some  multiple  of  CH2,  more  or  less.  In  examining  numbers  of  organic 
substances,  which  are  closely  related  to  each  other  in  their  properties,  we 


COMPOUNDS    OF   CARBON. 


147 


find  that  we  can  arrange  the  great  majority  of  them  in  series,  each  term 
of  which  differs  from  the  one  below  it  by  CH2;  such  a  series  is  called  an 
homologous  series.  It  will  be  readily  understood  that  such  an  arrange- 
ment in  series  vastly  facilitates  the  remembering  of  the  composition  of 
organic  bodies.  In  the  following  table,  for  example,  are  given  the  satu- 
rated hydrocarbons  and  their  more  immediate  derivatives.  At  the  head 
of  each  vertical  column  is  an  algebraic  formula,  which  is  the  general 
formula  of  the  entire  series  below  it;  n  being  equal  to  the  numerical 
position  in  the  series.  The  chemist  is  not  obliged  to  burden  his  memory 
with  all  the  formulae  in  the  table,  but  simply  to  remember  the  algebraic 
formulae.  The  name  of  the  substance  conveys,  in  most  instances,  to  his 
mind  the  series  to  which  it  belongs,  and  its  position  in  that  series;  and 
by  the  aid  of  the  algebraic  formula,  or  general  formula  as  it  is  called,  its 
composition  is  found  in  a  moment. 


HOMOLOGOUS  SERIES. 


Saturated  hydro- 
carbons, 
CnH2n+2. 

Alcohols, 
CnHan+aO. 

Aldehydes, 
CnH2nO. 

Acids, 
CnII3n02. 

Ketones, 
CnH3nO. 

CHi 

CH4O 

CO»H2 

C.H6 

C2H6O 

C2H4O 

C2O.2H4 

C3H8 

C4Hi0 

C5H12 

C3H*0 
C4H10O 
C5H120 
C6H14O 

C3HGO 
C4H60 
C5H10O 
C6H10O 

C302H6 
C402H8 
CAH,  o 
C6O2Hi2 

CSH60 

C4H8O 
C5H10O 

C-H16 

C,H16O 

C7H14O 

CnOvTLu 

CfcH18 

C8H18O 

C6H16O 

C8O2H16 

C»H200 

C<,O2Hi8 

CnH24 

"° 

C    O-  H 

C14O2H28 

But  the  arrangement  in  homologous  series  does  more  for  us  than  this. 
The  properties  of  substances  in  the  same  series  vary  in  regular  gradation 
according  to  their  position  in  the  series;  thus,  in  the  series  of  alcohols  in 
the  above  table,  the  boiling-points  of  the  first  six  are,  66.5°,  78.4°,  96.7°, 
111.7°,  132.2°,  153.9°;  from  which  it  will  be  seen  that  the  boiling-point 
of  any  one  of  them  can  be  determined,  with  a  maximum  error  of  3°,  by 
taking  the  mean  of  those  of  its  neighbors  above  and  below.  In  this  way 
we  may  prophecy,  to  some  extent,  the  properties  of  a  wanting  member 
in  a  series  before  its  discovery.  The  terms  of  any  homologous  series 
must  all  have  the  same  constitution,  i.  e.9  their  constituent  atoms  must  be 
similarly  arranged  within  the  molecule. 


ISOMEEISM — METAMERISM — POLTMERISM. 

Two  substances  are  said  to  be  isomeric,  or  to  be  isomeres  of  each  other, 
when,  upon  analysis,  they  prove  to  have  the  same  centesimal  composition. 
If,  for  instance,  we  analyze  acetic  acid  and  methyl  formiate,  we  find  that 


148  GENERAL    MEDICAL    CHEMISTRY. 

each   body  consists  of   carbon,  oxygen,  and  hydrogen,  in  the  following 
proportions: 

Carbon 40  24=12  x  2 

Oxygen v, , 53 .33  32=16  x  2 

Hydrogen ;*....      C .  67  4=   4x1 


100.00  60 

This  similarity  of  centesimal  composition  may  occur  in  two  ways: 
the  two  substances  may  each  contain  in  a  molecule  the  same  numbers  of 
each  kind  of  atom  ;  or  one  may  contain  in  each  molecule  the  same  kind  of 
atoms  as  the  other,  but  in  a  higher  multiple.  In  the  above  instance,  for 
example,  each  substance  may  have  the  composition  C2H4O2;  or  one  may 
have  that  formula  and  the  other,  C6H12O6,  or  C2H4O2  x  3.  In  the  former 
case  the  substances  are  said  to  be  metameric,  in  the  latter  polymeric. 
Whether  two  substances  are  metameric  or  polymeric  can  only  be  de- 
termined by  ascertaining  the  weights  of  their  molecules,  which  is  usually 
accomplished  by  determining  the  specific  gravities  of  their  vapors  (sec 
p.  14). 

The  specific  gravity  of  the  vapor  of  acetic  acid  is  the  same  as  that  of 
methyl  formiate,  and,  consequently,  each  substance  is  made  up  of  mole- 
cules, each  containing  C3H4O0.  But  the  two  substances  differ  from  eacli 
other  greatly  in  their  properties,  and  their  differences  are  at  once  indi- 
cated by  their  typical  or  graphic  formulas:  , 


(C2H30)')Q  d          (CHO)')0. 

Hp  (CH3)'fU> 

or  graphically: 


CH.  H 

and 
.H  CO.OCH,. 


coo.: 


Polymeric  substances,  although  they  yield  the  same  result  upon  cen- 
tesimal analysis,  possess  different  molecular  weights,  that  of  one  being  a 
simple  multiple  of  that  of  the  other.  Acetic  acid  and  grape-sugar,  on 
analysis,  both  prove  to  have  the  same  centesimal  composition: 

Carbon 40.  12 

Oxygen  53 .33  16 

Hydrogen 6.67  2 


100.00  30 

but  the  molecular  weight  of  acetic  acid  is  60,  or  12x2  +  16x2  +  1x4, 
and  its  composition  is  therefor  C2O2H4.  The  molecule  of  grape-sugar 
weighs  180,  or  12x6  +  16x6  +  1x12,  and  its  composition  is  therefor 
C.O.H,,. 

CLASSIFICATION  OF  ORGANIC  SUBSTANCES. 

As  the  compounds  of  the  other  elements  may  be  divided  into  classes, 
such  as  acids,  bases,  salts,  etc.,  according  to  their  chemical  functions,  the 


COMPOUNDS    OF   CARBON".  149 

compounds  of  carbon  also  arrange  themselves  into  certain  well-defined 
groups,  called  by  the  French  chemists  functions — a  term  which  it  would 
be  well  to  introduce  into  our  own  nomenclature.  The  properties  of  the 
functions  of  organic  substances  do  not  depend,  like  those  of  other  com- 
pounds, upon  the  kind  of  atoms  of  which  they  are  composed,  but  rather 
upon  the  arrangement  of  the  atoms  within  the  molecule;  and  in  this 
point  we  find  the  most  prominent  distinction  between  organic  and  mineral 
substances.  Arsenic,  for  instance,  is  poisonous  in  whatever  form  of 
chemical  combination  it  may  be,  provided  only  that  it  can  be  rendered 
soluble,  and  therefor  capable  of  absorption.  Carbon,  oxygen,  and  hydro- 
gen, on  the  other  hand,  combine  with  each  other  to  form  substances  hav- 
ing the  most  diverse  action  upon  the  economy — the  fats  and  sugars, 
ordinary  articles  of  food,  on  the  one  hand,  and  substances  having  such 
marked  toxic  powers  as  ether  and  oxalic  acid,  on  the  other — the  differ- 
ences between  the  properties  of  the  two  substances  depending  entirely 
upon  the  numbers  and  positions  in  the  molecule  of  the  same  kind  of  atoms. 
Before  entering  upon  the  consideration  of  the  individual  compounds, 
and  to  render  what  follows  intelligible,  we  must  briefly  describe  the  gen- 
eral properties  of  these  different  functions. 


DERIVATIVES  OP  THE  SATURATED  HYDROCARBONS — COMPOUNDS  OF  UNI- 
VALENT RADICALS. 

Saturated  hydrocarbons. — A  hydrocarbon  is  a  compound  consisting 
of  carbon  and  hydrogen  only,  and  it  is  saturated  when  all  the  valences  of 
the  constituent  atoms  are  satisfied.  These  substances  belong  to  the 
homologous  series  of  which  marsh-gas  is  the  first  term,  and  which  has 
the  general  formula,  CnH2n+2.  Like  all  other  saturated  compounds, 
their  composition  cannot  be  modified  by  addition,  i.  e.,  by  the  simple  in- 
sertion of  other  atoms  into  the  molecule;  they  may,  however,  be  modified 
by  substitution,  i.  e.,  by  the  removal  of  one  or  more  of  their  atoms,  and 
the  substitution  therefor  of  one  or  more  atoms  of  a  different  kind.  Their 
composition  is  expressed  by  the  typical  formula: 


The  groups  CnHan+1,  containing  one  unsatisfied  valence,  are  univa- 
lent, and  are  the  radicals  of  which  these  hydrocarbons  are  the  hydrides. 
These  univalent  radicals,  more  or  less  modified  by  substitution,  enter  into 
the  composition  of  a  vast  number  of  important  substances,  which  are  thus 
said  to  be  derivatives  of  this  series  of  hydrocarbons.  These  radicals  are 
also  sometimes  designated  as  alcoholic,  as  they  exist  in  the  series  of  sub- 
stances of  which  ordinary  alcohol  is  the  type.  The  members  of  this  series 
are  sometimes  called  paraffines,  from  the  occurrence  of  the  higher  terms 
in  the  commercial  product  of  that  name  and  in  petroleum. 

Chlorides,  Bromides,  and  Iodides. — The  radicals  of  this  series  behave 
in  many  respects  like  atoms  of  a  univalent,  electro-positive  element,  and, 
like  them,  are  capable  of  uniting  with  an  atom  of  chlorine,  bromine,  or 
iodine,  to  form  chlorides,  bromides,  or  iodides. 

r,=(C,HJ'Br+BrH 

Bromine.  Ethyl          Hydrogen 

bromide.         bromide. 


150  GENERAL   MEDICAL    CHEMISTRY. 

These  substances  are  also  designated  as  haloid  ethers,  corresponding, 
as  they  do,  with  the  haloid  salts.  Several  of  them  are  used  medicinally. 

Alcohols.  —  The  name  alcohol,  formerly  applied  only  to  the  substance 
now  popularly  so  called,  has  gradually  come  to  be  used  to  designate  a 
large  class  of  important  bodies,  of  which  vinic  alcohol  is  the  representa- 
tive. These  substances  are  mainly  characterized  by  their  power  of  enter- 
ing into  double  decomposition  with  acids,  to  form  neutral  compounds, 
called  compound  ethers,  water  being  at  the  same  time  formed,  at  the 
expense  of  both  alcohol  and  acid.  They  are  the  hydrates  of  the  alcoholic 
radicals,  and  as  such  resemble  the  metallic  hydrates,  while  the  compound 
ethers  are  the  counterparts  of  the  metallic  salts: 


Ethyl  hydrate.  Acetic  acid.  Ethyl  acetate.  Water. 


Potassium  Acetic  acid.  Potassium  Water. 

hydrate.  acetate. 

As  the  metallic  hydrates  may  be  considered  as  formed  by  the  union 
of  one  atom  of  the  metallic  element  with  a  number  of  groups  OH',  cor- 
responding to  its  valence,  so  the  alcohols  are  formed  by  union  of  an  un- 
oxidized  radical  with  a  number  of  groups  OH',  equal  to  or  less  than  the 
number  of  free  valences  of  the  radical.  When  the  alcohol  contains  one 
OH,  it  is  designated  as  monoatomic;  when  two,  diatomic'  when  three, 
triatomic,  etc. 

The  simplest  alcohols  are  those  derivable  from  the  saturated  hydro- 
carbons, and  having  the  general  formula  CnH2W4.aO,  or  CnH27l+1OH.  The 
terms  of  this  series,  which  contains  vinic  alcohol,  may  be  forujed  synthet- 
ically : 

First.  —  By  acting  upon  the  corresponding  iodide  with  potassium  hy- 
drate : 

CaH6I+KHO=KI+CaH5OH. 

Second.  —  From  the  alcohol  next  below  it  in  the  series,  by  direct  addi- 
tion of  CH2,  only,  however,  by  a  succession  of  five  reactions. 

Third.  —  By  the  action  of  sulphuric  acid  and  water  upon  the  corre- 
sponding hydrocarbon  of  the  series  CnHsn. 

The  saturated  monoatomic  alcohols  are,  however,  not  limited  to  one 
corresponding  to  each  alcoholic  radical.  It  has  been  found  that  there 
exist  —  corresponding  to  the  higher  alcohols  —  a  number  of  substances 
having  the  same  centesimal  composition  and  the  same  alcoholic  prop- 
erties, and  differing  only  in  their  physical  characters  and  in  their  pro- 
ducts of  decomposition  and  oxidation.  These  isomeres  have  been  the 
subject  of  much  careful  study  of  late  years.  It  has  been  found  that  the 
molecules  of  methyl,  ethyl,  and  other  higher  alcohols  are  made  up  of  the 
group  (CH3OH)'  united  to  H  or  to  CnH,n+1,  thus: 

CHOH  CHOH  CHOH 


a  2  2 

H  in  6H 


,5 

Methyl  alcohol.  Ethyl  alcohoL  Propyl  alcohol. 


COMPOUNDS    OF    CARBON.  151 

and  all  monoatomic  alcohols  containing  this  group,  CHaOH,  have  been 
designated  as  primary  alcohols.  Isomeric  with  these  are  other  bodies, 
which,  in  place  of  the  group  (CH2OH)',  contain  the  group  (CHOH)", 
which  are  distinguished  as  secondary  alcohols.  Thus  we  have: 

CH3 
(CHOH)' 

(CHOH)" 

H. 
C3H80  C3H80 

Primary  Secondary 

propyl  alcohol.  propyl  alcohol. 

And,  further,  other  substances  are  known,  which  contain  the  group 
(COH)'",  and  which  are  called  tertiary  alcohols,  thus: 

(CH.OH)'  C,H.  CH, 

C.H,  (OHOH)"          (C,H.)— (COH)'" 

C,H.  CH, 

O.H..O  C.H.,0  C.H.,0 

Primary  amylic  Secondary  amylic  Tertiary  amylic 

alcohol.  alcohol.  alcohol. 

The  alcohols  of  these  three  classes  are  distinguished  from  each  other 
principally  by  their  products  of  oxidation.  The  primary  alcohols  yield 
by  oxidation,  first  an  aldehyde  and  then  an  acid,  each  containing  the 
same  number  of  atoms  of  carbon  as  the  alcohol,  and  formed,  the  aldehyde 
by  the  removal  of  H2  from  the  group  (CH2OH),  and  the  acid  by  the  sub- 
stitution of  O  for  Ha  in  the  same  group,  thus: 

CH3OH  COH  COOH 

CH3  CH3  CH3 

Ethyl  alcohol.  Ethyl  aldehyde.  Acetic  acid 

In  the  case  of  the  secondary  alcohols,  the  first  product  of  oxidation  is  a 
Jcetone,  containing  the  same  number  of  atoms  of  carbon  as  the  alcohol,  and 
formed  by  the  substitution  of  O  for  HOH  in  the  distinguishing  group: 

CH,  CH, 

CHOH  CO 

CH3  CH3 

Secondary  propyl  Propyl  ketone 

alcohol.  or  acetone. 

The  tertiary  alcohols  yield  by  oxidation  ketones  or  acids,  whose  mole- 
cules contain  a  less  number  of  atoms  of  carbon  than  the  alcohol  from 
which  they  are  derived. 


152  GENERAL    MEDICAL    CHEMISTRY. 

But  the  complication  does  not  end  here;  isomeres  have  been  found  to 
exist  corresponding"  to  the  higher  alcohols,  which  are  themselves  primary 
alcohols,  and  contain  the  group  (CH2OH)'.  It  has  been  shown  by  recent 
investigation  that  there  exist  no  less  than  seven  distinct  substances,  all 
having  the  centesimal  composition  of  amyl  alcohol,  C5II12O,  and  the  prop- 
erties of  alcohols;  and  theoretical  considerations  point  to  the  probable  ex- 
istence of  an  eighth.  Of  these  eight  substances,  four  are  primary,  three 
secondary  alcohols,  and  the  remaining  one  a  tertiary  alcohol.  As  each  of 
these  bodies  contains  the  group  of  atoms  characteristic  of  the  class  of 
alcohol  to  which  it  belongs,  it  is  obvious  that  the  differences  observed  in 
their  properties  are  due  to  differences  in  the  arrangement  of  the  other 
atoms  of  the  molecule.  Experimental  evidence,  which  it  would  require 
too  much  space  to  discuss  in  this  place,  has  led  chemists  to  ascribe  the 
following  formulas  of  constitution  to  these  isomeres: 

Primary  amylic  alcohols  : 

CH3—  CH3—  CH2—  CH2—  CH3,OH 

Normal  amylic  alcohol. 

8CH~  CHa—  CH2,OH 


2, 

Active  amylic  alcohol  of  fermentation. 


CH, 
GET 


3 

Inactive  amylic  alcohol  of  fermentation. 


CH3— C— CH,,OH 
CH3/ 

"Unknown. 


Secondary  amylic  alcohols  : 


Diethyl  carbinol. 


CH8—  CH2—  CH*/CH>OH 

Methyl-propyl  carbinol. 


CH/ 

Methyl-isopropyl  carbinol. 


Tertiary  amyl  alcohol : 

CH,\ 
CHS— C,OH 
CH.-CH,/ 

For  alcohols  of  other  series,  see  pp.  230,  274. 

Simple  Ethers. — These  bodies  are  the  oxides  of  the  alcoholic  radicals, 


COMPOUNDS    OF    CARBON.  153 

and  in  constitution  bear  the  same  relation  to  the  alcohols  that  the  oxides 
of  basylous  elements  bear  to  their  hydrates: 


Ethyl  oxide  Ethyl  hydrate 

(ethylic  ether).  (alcohol). 

K 
K 

Potassium  oxide.  Potassium  hydrate. 

When  the  two  alcoholic  radicals  are  the  same,  as  in  the  above  in- 
stance, the  ether  is  designated  as  simple;  when  they  are  different,  as  in 

/^|TT       \ 

methyl-ethyl  oxide,  p  TTS  J-  O,  they  are  called  mixed  ethers. 

Monobasic  Acids. — By  the  action  of  oxidants  upon  the  primary  mono- 
atomic  alcohols,  one  atom  of  oxygen  is  substituted  for  H2  in  the  group 
CH2OH,  with  the  formation  of  substances  having  the  functions  of  acids, 
and  containing  in  each  molecule  one  atom  of  replaceable  hydrogen: 

CH8— CH2— CH2— CH2— CHa,OH 

Normal  amylic  alcohol . 

CH3— CH2— CH2— CH2— CO,OH 

Normal  yalerianic  acid. 

The  introduction  of  the  atom  of  oxygen  communicates  electro-nega- 
tive qualities  to  that  portion  of  the  molecule  other  than  OH,  to  the  radi- 
cal; in  other  words: 


Amylic  alcohol.  Valcrianic  acid. 

And  it  is  to  this  electro-negative  nature  of  the  radical,  that  the  substance 
owes  its  acid  nature. 

The  acids  formed  by  the  oxidation  of  the  primary  alcohols,  have  the 
general  formula 

C,H,A,         or  C"H-°}0 

Compound  Ethers. — As  the  alcohols  resemble  the  mineral  bases,  and 
the  organic  acids  resemble  those  of  mineral  origin,  so  the  compound 
ethers  are  similar  in  constitution  to  the  salts,  being  formed  by  the  double 
decomposition  of  an  alcohol  with  an  acid,  mineral  or  organic,  as  a  salt 
is  formed  by  double  decomposition  of  an  acid  and  a  mineral  base,  the 
radical  playing  the  part  of  an  atom  of  corresponding  valence. 


Potassium  hydrate.  Nitric  acid.  Water.  Potassium  nitrate. 


154 

(<W  t  ( 


GENERAL    MEDICAL    CHEMISTRY. 


Ethyl  hydrate 
(alcohol). 


(NOJ 


o     = 


Nitric  acid. 


II 


H  t 

Water. 


0 


(NO,) 


O,)  )  Q 

A)'  \  c 


Ethyl  nitrate 
(nitric  ether;. 


Ethyl  hydrate. 


Acetic  acid. 


Water. 


Ethyl  acetate 
(acetic  ether). 


Aldehydes.  —  It  will  be  remembered  that  the  monobasic   acids   are 
obtained  from  the  alcohols  by  oxidation  of  the  radical: 


WJo 


ji  j 


0 


Ethyl  alcohol. 


Acetic  acid. 


These  oxidized  radicals  are  capable  of  forming  compounds  similar  in  con- 
stitution to  those  of  the  non-oxidized  radicals.     There  are  chlorides,  bro- 

ir\  TT  Q\  •) 

mides,  and  iodides  ;  their  hydrates  are  the  acids,  ^    a     8  TT  r  O,  =  acetic 

(C*  TT  (~M  ) 
acid;  their  oxides  are  known  as  anhydrides,  \r^^{r\\  [  O  =  acetic  anhy- 

(C*  TT  O^  ) 
dride  ;  and  their  hydrides  are  the  aldehydes  ^    2    3  TT  [•  —  acetic  aldehyde, 

the  name  aldehyde  being  a  corruption  of  alcohol  dehydrogenatum,  from 
the  method  of  their  formation,  by  the  removal  of  hydrogen  from  alcohol. 
The  aldehydes  all  contain  the  group  of  atoms  (COH)',  and  their  con- 
stitution may  be  thus  graphically  indicated  : 


COH 


COH 

I 
OH, 

CH. 


Acetic  aldehyde. 


Propionic  aldehyde. 


They  are  capable,  by  fixing  H2,  of  regenerating  the  alcohol  ;  and,  by 
fixing  O,  of  forming  the  corresponding  acid: 


COH 


b 


CH2OH 


Acetic  aldehyde. 


Ethylic  alcohol. 


CO,OH 


{. 


Acetic  acid. 


Ketones  or  Acetones. — Although  the  aldehydes  are  not  acid  in  reaction, 
and  are  not  usually  regarded  as  acids,  there  exists  a  number  of  substances 
known  as  ketones  or  acetones,  which  may  be  regarded  as  formed  by  the 
substitution  of  an  alcoholic  radical  for  the  hydrogen  of  the  group  COH. 


COMPOUNDS    OF   CARBON.  155 

These  substances  all  contain  the  group  of  atoms  (CO)",  and  their  con- 
stitution may  be  represented  graphically  thus  : 


CH, 

c 

Ao 

in. 

OH, 

AH, 

Dimethyl  kctone 
(acetone). 

Methyl-ethyl  ketone. 

The  first  being  a  symmetrical  ketone  and  the  latter  a  non-symmetrical. 
The  ketones  are  isomeric  with  the  aldehydes,  from  which  they  are  dis- 
tinguished :  1st,  by  the  action  of  hydrogen,  which  produces  a  primary 
alcohol  with  an  aldehyde,  and  a  secondary  alcohol  with  a  ketone: 

COH  CHaOH 


, 

OTT  r<"H" 

u±±3  ^^3 

Propionic  aldehyde.  Propyl  alcohol. 


A 


CH, 

+     Ha     -    CH,OH 
H. 


••3 

Acetone.  Isopropyl  alcohol. 


2d,  by  the  action  of  oxygen,  which  unites  directly  with  an  aldehyde  to 
produce  the  corresponding  acid,  while  it  causes  the  disruption  of  the  mole- 
cule of  a  ketone,  with  formation  of  two  acids: 


COH 

CO,OH 

CH       4- 

O     =     CHa 

CH 

3 

CH3 

Propionic  aldehyde. 

Propionic  aci 

CH, 

CO,OH        CO,OH 
CO    +  O,  =    I  +    I 

I  H  CH3 

CH3 

Acetone.  Formic  acid.  Acetic  acid. 

Amines  or  compound  ammonias.  —  The  monamines  are  substances 
which  may  be  considered  as  being  derived  from  one  molecule  of  ammonia 
by  the  substitution  of  one,  two,  or  three  alcoholic  radicals  for  one,  two,  or 


156  GENERAL    MEDICAL    CHEMISTRY. 

three  atoms  of  hydrogen.     They  are  designated  as  primary,  secondary, 
and  tertiary,  according  as  they  contain  one,  two,  or  three  alcoholic  radicals: 

H  H  H  CH-CH 


N-CH- 


N-H        N-CHa-CH3        N--CH2-CH3         N-CH2-CH, 
H  H  CHa-CH3  CHa-CH3 

NH8  (C2H5)H2,N  (C2HB)2H,N  (C2H5)3N, 

Ammonia.  Ethylamine  Diethylamine  Triethylamine 

(primary).  (secondary).  (tertiary). 

These  bodies  closely  resemble  ammonia  in  their  chemical  properties  ; 
they  unite  with  acids,  without  elimination  of  water,  to  form  salts  resem- 
bling those  of  ammonium.  They  also  unite  with  water  to  form  com- 
pounds, called  quaternary  ammonium  hydrates,  similar  in  constitution 
to  ammonium  hydrate. 

Although  the  amines  of  this  series  are  chiefly  of  theoretical  interest, 
other  series  contain  substances  of  great  practical  importance  (see  p.  346). 

Amides. — These  bodies  differ  from  the  amines  in  containing  oxygen- 
ated, or  add  radicals,  in  place  of  alcoholic  radicals.  Like  the  amines, 
they  are  divisible  into  primary,  secondary,  and  tertiary.  They  are  the 
nitrides  of  the  acid  radicals,  as  the  amines  are  the  nitrides  of  the  alcoholic 
radicals. 

The  monamides  may  also  be  regarded  as  the  acids  in  which  the  OH  of 
the  group  COOH  has  been  replaced  by  (NH2) : 

CH,  CH9 

COOH  CONH, 

Acetic  acid.  Acetamide. 

(For  other  amides  see  p.  256.) 

Amido-acids  or  Glycocols. — These  are  compounds  of  mixed  function, 
obtained  by  the  substitution  of  the  univalent  group  (NHa)',  for  an  atom 
of  radical  hydrogen  of  an  acid: 

CH3  CH2(NHa) 

COOH  COOH 

Acetic  acid.  Amido-acetic  acid ;  glycocol. 

Some  of  them,  and  many  of  their  derivatives,  exist  in  animal  bodies. 
Corresponding  to  them  are  many  isomeres  belonging  to  other  series. 


METHYL    HYDRIDE. 


157 


SATURATED  HYDROCARBONS. 

SERIES  CNH2N+2. 

The  members  of  this  series  are  the  most  simply  constituted  of  organic 
substances.  They  exist  in  nature  chiefly  as  products  of  what  is  com- 
monly regarded  as  the  mineral  kingdom,  and  constitute  the  inflammable 
gases  and  rock-oils  which  issue  from  the  earth  in  Pennsylvania,  Russia, 
and  other  places. 

The  following  is  a  list  of  the  members  of  this  group  at  present  known: 


Name. 

Formula. 

Specific  gravity  of 
liquid. 

Boiling-point 
Centigrade. 

Methyl  hydride  

CHH 

Ethyl  hydride  

CJBLH 

Propyl  hydride  

CXH 

I3utyl  hydride         . 

CHH 

0.600  at  0° 

0° 

Amyl  hydride  

CH  H 

0.628  at  18° 

30° 

Hexyl  hydride  

\j  ii    Jti 

0.669  at  18° 

68° 

Heptyl  hvdride  

C7H  H 

0.690  at  18° 

92°  —  94° 

Octyl  hvdride  

CHH 

0.726  at  18° 

116°—  118° 

Nonyl  hydride  

C.H.H 

0.741  at  18° 

136°—  138° 

Uecyl  hydride  .... 

CHH 

0.757  at  18° 

158°  162° 

Undecyl  hydride  

CV'H 

0.766  at  18° 

180°  —  182° 

Dodecyl  hydride  

O    rd    ri 

0.778  at  18° 

198°  —  200° 

Tridecyl  hydride  

CHH 

0.796  at  18° 

218°—  220° 

Tetradecyl  hydride  

CHH 

0.809  at  18° 

236°  —  240° 

Pentadecyl  hydride  

C"H"H 

0.825  at  18° 

258°  —  262° 

Hexadecyl  hydride  

C  H  H 

about  280° 

Methyl  Hydride. 

Methane — Marsh-gas — Light     carburetted    hydrogen — Fire-damp — 

/pTT    \     \ 

CH4   or  ^   -pr3'  >- . — It  is  given  off  from  decomposing  vegetable  matter  in 

swamps  and  bogs.     Volta,  in  1778,  first  recognized  the  individuality  of 
the  inflammable  gas  observed  in  such  situations. 

The  fire-damp,  which  has  been  the  cause  of  such  terrible  loss  of  life 
in  coal-mines,  is  a  mixture  composed  almost  entirely  of  methyl  hydride 
and  air,  in  varying  proportions.  In  many  localities  in  the  vicinity  of 
coal  or  petroleum  deposits,  and  in  some  instances  at  considerable  dis- 
tances from  such  formations,  there  issue  large  volumes  of  inflammable 
gases  from  fissures  and  borings  in  the  earth.  These  gases  consist  of  methyl 
hydride,  mixed  with  the  higher  members  of  the  series.  If  the  latter  be 
present  in  notable  proportions,  the  flame  of  the  gas  is  luminous,  and  may 
be  utilized  for  illuminating  purposes.  Illuminating  gas,  obtained  from 


158  GENERAL    MEDICAL    CHEMISTRY. 

the  distillation  of  coal,  contains  from  thirty-six  to  fifty  per  cent,  of  this 
gas  (see  p.  287). 

When  desired  in  a  state  of  purity,  marsh-gas  is  best  obtained  by  heat- 
ing strongly  a  mixture  of  sodium  acetate  and  sodium  hydrate,  each  one 
part,  and  quicklime  one  and,  pne-half  ^parts,  and  collecting  the  gas  over 
water: 

CaH3OaNa  +  NaHO  =  CO3Na2 


Methyl  hydride  is  a  colorless,  odorless,  tasteless  gas;  very  sparingly 
soluble  in  water;  more  soluble  in  alcohol;  sp.  gr.  0.559  A. 

Like  all  the  members  of  this  series,  marsh-gas  is  a  very  stable  sub- 
stance, and  is  not  readily  attacked  by  reagents;  it  is  for  this  reason  that 
the  name  paraffines  (from  parum,  little,  and  affinis,  related  to  by  mar- 
riage) has  been  applied,  particularly  to  the  higher  terms  of  the  series,  and 
recently  to  the  entire  series. 

At  high  temperatures  it  is  decomposed  into  carbon  and  hydrogen: 


Its  decomposition  takes  place  at  much  lower,  but  still  elevated,  temper- 
atures when  it  is  mixed  with  air  or  oxygen.  It  burns  in  air  with  a  pale 
yellow  flame,  which  is  extinguished  when  cooled.  Advantage  is  taken  of 
this  in  the  construction  of  miners'  safety-lamps,  in  which  the  flame  is  en- 
closed in  a  cage  of  fine  wire-gauze,  which,  by  its  cooling  effect,  prevents 
the  transmission  of  flame  from  the  lamp  outward.  If  a  mixture  of  marsh- 
gas  and  oxygen  (or  air)  be  heated  at  a  single  point  by  the  passage  of  the 
electric  spark,  or  by  the  approach  of  a  flame,  instant  decomposition  of  the 
entire  mass  takes  place,  with  a  violent  explosion,  and  the  formation  of 
carbon  dioxide  and  water: 


The  formation  of  immense  volumes  of  carbon  dioxide  in  this  way,  in  mine- 
explosions,  produces  what  is  known  to  miners  as  after-damp,  usually  fatal 
to  those  who  have  escaped  the  violence  of  the  explosion  itself. 

Chlorine  has  no  action  upon  marsh-gas  in  the  dark  and  cold;  under 
the  influence  of  diffuse  daylight,  however,  one  or  more  of  the  atoms  of 
hydrogen  are  replaced  by  an  equivalent  quantity  of  chlorine.  In  direct 
sunlight  the  change  takes  place  with  an  explosion.  The  higher  terms  of 
this  series  are  of  interest  principally  as  constituting  petroleum  and  allied 
bodies  obtained  therefrom. 


Petroleum. 

(From  7T€T/?a,  a  rock,  and  oleum,  oil.)  Mineral  oils  have  been  known 
from  the  remotest  antiquity,  and  were  obtained  from  the  vicinity  of  Agri- 
gentum,  in  Sicily,  from  the  Island  of  Zacynthus,  in  the  Ionian  Sea,  and 
from  Persia,  for  use  as  a  medicine  and  for  burning  in  lamps.  In  later 
times  petroleum  was  found  in  various  parts  of  Europe,  Asia,  and  South 
and  North  America.  It  is  only,  however,  since  1859  that  rock-oil  has  be- 
come the  commercially  important  substance  that  it  now  is.  In  1853  at- 
tention was  first  drawn  to  the  existence  of  petroleum  in  Pennsylvania,  and 
from  that  date  until  1859  attempts  were  made  to  obtain  the  oil  by  the  old 


PETROLEUM.  159 

Indian  method  of  sinking  square  pits  into  the  earth,  in  which  cloths  were 
then  placed  until  saturated  with  the  oil,  which  was  then  wrung  out. 

In  1859  the  oil  fever  was  inaugurated  with  the  sinking  of  a  well  sev- 
enty-five feet  deep  near  Titusville,  from  which  ten  barrels  or  four  hundred 
and  thirty  gallons  of  oil  were  obtained  daily.  A  great  number  of  wells 
were  now  sunk  at  various  points  in  the  Oil  Creek  Valley,  and  with  such 
success  that  the  production  during  the  first  year  amounted  to  eighty-two 
thousand  barrels,  or  over  three  and  one-half  millions  of  gallons.  From 
that  time  to  the  present  the  production  of  oil  has  steadily  increased. 

The  production  is  not  limited  to  Pennsylvania,  large  quantities  being 
obtained  from  Ohio,  Western  New  York,  West  Virginia,  Lower  Canada, 
as  well  as  from  California,  Burmah,  Borneo,  and  the  shores  of  the  Caspian 
Sea.  The  oil  obtained  in  different  localities  varies  in  composition.  In 
the  American  oil  districts  the  oil  is  obtained  from  either  flowing  or  pump- 
ing wells,  the  former  of  which  yield  enormous  quantities  of  oil,  but  cease 
flowing  after  a  time.  The  famous  Empire  well  flowed  from  1862  to  1866, 
and  yielded  two  thousand  barrels,  or  eighty-six  thousand  gallons,  per 
diem.  In  its  deposits  the  oil  is  associated  with  salt  water  and  gaseous 
hydrocarbons,  forming  a  layer  upon  the  surface  of  the  water.  When  the 
deposit  occurs  in  a  closed  pocket,  the  pressure  of  the  gas  is  sufficient  to 
force  through  a  tube  penetrating  the  cavity  either  water,  oil,  or  gas,  as 
the  end  of  the  tube  is  in  one  or  another  layer. 

The  crude  petroleum,  as  it  comes  from  the  well,  is  a  highly  inflammable 
substance,  differing  in  composition  and  in  physical  properties  in  the 
products  of  different  wells,  even  in  the  same  section  of  country.  It  varies 
in  color  from  a  faintly  yellowish  tinge  to  a  dark  brown,  nearly  black, 
with  greenish  reflections.  The  lighter-colored  varieties  are  limpid,  and 
the  more  highly  colored  of  the  consistency  of  thin  syrup.  The  specific 
gravity  varies  from  0.74  to  0.92.  The  composition  of  crude  petroleums 
has  been  the  subject  of  a  great  deal  of  investigation;  they  have  been 
found  to  contain  all  the  hydrocarbons  mentioned  in  the  list  on  p.  157, 
(the  first  of  the  series,  being  found  in  the  gases  accompanying  petroleum, 
is  also  held  in  solution  by  the  oil  under  the  pressure  it  supports  in  natural 
pockets),  besides  hydrocarbons  of  the  olefine  series  (see  p.  227),  and  of 
the  benzol  series  (see  p.  315). 

The  crude  oil  is  highly  inflammable,  usually  highly  colored,  and  is 
prepared  for  its  multitudinous  uses  in  the  arts  by  the  processes  of  dis- 
tillation and  refining;  which,  in  the  case  of  the  American  oils,  are  con- 
ducted at  the  three  principal  refineries  at  Cleveland,  O.,  New  York,  and 
Pittsburg,  Pa.,  to  which  points  the  mixed  oils  from  various  wells  are 
conveyed  by  boat,  rail,  or  lines  of  pipes. 

The  process  of  distillation  is  usually  so  conducted  as  to  divide  the 
crude  oil  into  four  parts: 

Naphtha sp.gr.  0.700  at  15°  C 12—15  per  cent. 

Benzine sp.  gr.  0.730  at  15°  C 9—12  per  cent. 

Burning-oil.  . .  .sp.  gr.  0.783  at  15°  C.     about  60  per  cent. 

Residuum  and  loss about  13 — 19  per  cent. 

The  naphtha,  also  known  as  petroleum  ether,  is  by  further  fractional 
distillation  again  subdivided  into  other  products: 

Hhigolene,  a  highly  volatile  and  inflammable  liquid,  which  boils  at 
21°  C;  =70°  F.,  and  has  a  specific  gravity  of  about  0.60  =  90°— 97° 
Baume.  It  has  been  used  as  a  substitute  for  ether  to  produce  cold  by 


1GO  GENEEAL    MEDICAL    CHEMISTRY. 

evaporation.  It  should  be  kept  in  a  situation  where  the  temperature 
does  not  rise  above  its  boiling-point,  and  should  be  handled  with  caution, 
as  its  vapor  forms  an  explosive  mixture  with  air. 

Gasoline,  also  obtained  from  naphtha,  boils  at  76.6°  C.  =  170°  F.,  and 
has  a  specific  gravity  of  0.-63 — 0.61  =  80° — 90°  Baume,  and  is  used,  as  its 
name  implies,  for  the  manufacture  of  illuminating  gas. 

Benzine,  or  benzoline,  is  a  colorless  liquid,  boiling  at  148°  C.=:2980  F., 
having  a  specific  gravity  of  0.73  =  60°  Baume,  and  a  peculiar  odor.  It  is 
largely  used  in  the  arts  as  a  solvent  for  fatty  substa-nces.  It  must  not  be 
confounded  with  benzene  or  benzol,  which  is  a  totally  different  substance, 
obtained  from  coal-tar  (see  p.  315).  The  two  substances  resemble  each 
other  in  appearance,  but  maybe  distinguished  by  the  following  characters: 


BENZOLINE. 
Boils  at  about  140°  C.,  sp.  gr.  0.69—0.73, 


BENZENE. 
Boils  at  80°  C.,  sp.  gr.   0.88,    or  30° 


or  GO0  to  70°  Baume;  does  not  crystallize    Baume;  crystallizes  at  3.2°  C. 
at  the  freezing-point  of  water. 

Smells  of  petr  leum  ;  does  not  sensibly  Smells  of  coal-tar ;  dissolves  pitch 
dissolve  pitch  or  absolute  carbolic  acid  in  i  readily,  forming  a  dark  brown  solution, 
the  cold.  i  Is  miscible  with  absolute  carbolic  acid  in 

I  all  proportions. 

The  most  important  product  of  petroleum  is  that  portion  which 
passes  over  at  temperatures  above  183°  C.,  and  which  constitutes  what 
is  usually  known  as  kerosene — various  other  trade-names  being  applied  to 
it  in  different  degrees  of  purity,  and  by  different  manufacturers.  In  the 
manufacture  of  these  burning-oils  care  must  be  had  that  the  more  volatile 
compounds  are  separated,  and  that  the  temperature  be  not  pushed  too 
high;  in  the  latter  case  the  oil  is  "  cracked, "  i.  <?.,  the  denser  oils  remain- 
ing in  the  still  are  dissociated,  forming  highly  volatile  compounds,  which 
mix  with  the  product.  In  either  case  the  kerosene  is  liable  to  give  rise 
to  accidents,  either  by  igniting,  in  case  the  lamp  is  broken  or  overturned, 
and,  in  very  bad  oils,  by  forming  with  air  a  mixture  which  may  explode 
the  lamp.  In  order  to  guard  against  such  accidents,  laws  have  gradu- 
ally been  framed  in  various  States  and  countries,  regulating  the  manufac- 
ture, transportation,  and  storage  of  these  oils.  The  tests  to  which  they 
are  subjected  relate  to  the  temperature  at  which  they  give  off  inflamma- 
ble vapors  and  that  at  which  they  ignite.  The  tests  are  applied  by 
gradually  warming  the  oil,  and  noting  the  temperature,  indicated  by  a 
thermometer  plunged  in  it,  at  the  time  when  a  lighted  match,  carried  over 
its  surface,  produces  a  flash,  and  the  temperature  when  the  oil  itself 
ignites;  the  former  is  known  as  the  "flashing-point,"  the  latter  as  the 
"burning-point;"  the  former  is  about  5°— 8°  C.  =  10°— 15°  F.  below  the 
latter.  It  was  formerly  supposed  that  an  ail  flashing  at  43°  C.  =  110° 
F.  was  safe  ;  but  subsequent  experience  has  shown  that  kerosene  gives 
off  explosive  vapors  at  a  temperature  5° — 8°  C.  =  10° — 15°  F.  below  its 
flash-point,  and  14° — 17°  C.  =  25° — 30°  F.  below  its  burning- point,  and 
serious  accidents  have  resulted  from  the  use  of  oils  of  110°  flash.  A 
kerosene  is  now  required,  therefor,  to  have  a  flash-point  of  60°  C.  — 
140°  F.,  and  a  burning-point  of  65.5C.  =  150°  F.;  an  oil  of  lower  test  is 
unsafe. 

If  the  oil  be  colored,  as  is  usually  the  case,  it  is  purified — refined — by 
heating  with  sulphuric  acid,  and  then  with  caustic  soda.  The  neigh- 
borhood of  petroleum  refineries,  as  residents  of  New  York  are  aware,  is 
frequently  infected  with  disgusting  and  deleterious  odors,  emanating 


METHYL    CHLOKIDE.  161 

partly  from  the  waste  acid  used  in  the  refining,  and  partly  from  the  va- 
pors issuing  from  the  stills  when  the  oil  is  purposely  "  cracked,"  that  a 
greater  yield  of  kerosene  may  be  obtained. 

From  the  residue  remaining  after  the  separation  of  the  kerosene,  a 
variety  of  other  products  are  obtained.  Lubricating  oils,  of  too  high 
boiling-point  for  use  in  lamps.  Paraffine,  a  white,  crystalline  solid,  fusi- 
ble at  45° — 65°,  which  is  used  in  the  arts  for  a  variety  of  purposes  for- 
merly served  by  wax,  such  as  the  manufacture  of  candles.  In  the  lab- 
oratory it  is  very  useful  for  coating  the  glass  stoppers  of  bottles,  and 
for  other  purposes,  as  it  is  not  affected  by  acids  or  by  alkalies.  It  is 
odorless,  tasteless,  insoluble  in  water  and  in  cold  alcohol ;  soluble  in  boil- 
ing alcohol  and  in  ether,  fatty  and  volatile  oils,  and  mineral  oils.  It  is 
also  obtained  by  the  distillation  of  certain  varieties  of  coal,  and  is  found 
in  nature  in  fossil  wax  or  ozocerite. 

The  products  known  as  vaseline,  cosmoline,  etc.,  which  are  now  so 
largely  used  in  pharmacy  and  perfumery,  are  mixtures  of  paraffine  and 
the  heavier  petroleum  oils.  Like  petroleum  itself,  its  various  commercial 
derivatives  are  not  definite  compounds,  but  mixtures  of  the  hydrocarbons 
of  this  series. 


CHLORINE,    BROMINE,    AND    IODINE    DERIVATIVES    OP 
HYDROCARBONS  OF  THE  SERIES  CnH2n+2. 

By  the  action  of  bromine  upon  the  hydrocarbons  of  this  series,  or  by 
the  action  of  hydrochloric,  hydrobromic,  or  hydriodic  acid  upon  the  cor- 
responding hydrate,  compounds  are  obtained  in  which  one  atom  of  hydro- 
gen of  the  hydrocarbon  is  replaced  by  an  atom  of  chlorine,  bromine,  or 
iodine: 

C2H6       +  Br2     =  C2H5Br  +  HBr, 

Ethyl  Bromine.  Ethyl          Hydrobromic 

hydride.  bromine.  acid. 

C2H6OH  +  HC1  =  C2H&C1  +  HaO, 

Ethyl          Hydrochloric          Ethyl  Water, 

hydrate.  acid.  chloride. 

These  substances  are  also  known  as  haloid  ethers. 


Methyl  Chloride—  CH3C1, 

Is  obtained  as  a  colorless  gas,  slightly  soluble  in  water,  and  having  a  sweet- 
ish odor  and  taste,  by  distilling  together  sulphuric  acid,  sodium  chloride, 
and  methylic  alcohol;  also,  on  a  commercial  scale,  from  the  residues  of  the 
manufacture  of  beet-sugar.  Under  the  influence  of  cold  it  forms  a  liquid 
which  boils  at  —22°. 

It  is  inflammable,  and  burns  with  a  greenish  flame.  When  mixed  with 
chlorine  and  exposed  to  sunlight,  a  further  substitution  of  chlorine  for 
hydrogen  takes  place.  When  heated  with  potassium  hydrate,  it  is  con- 
verted into  methyl  hydrate. 


162  GENERAL    MEDICAL    CHEMISTRY. 


Methyl  Bromide— CH3Br. 

A  colorless  liquid;  boils  at  13°;  sp.  gr.  1.664;  has  an  ethereal  and  faintly 
alliaceous  odor;  prepared  by  the  combined  action  of  phosphorus  and  bro- 
mine upon  methyl  hydrate. 


Methyl  Iodide— CH3I. 

A  colorless  liquid;  boils  at  about  45°;  sp.  gr.  2,237;  burns  with  diffi- 
culty, giving  off  violet  vapors  of  iodine.  It  is  prepared  by  a  process  sim- 
ilar to  that  used  for  obtaining  the  bromide.  It  is  used  in  the  laboratory, 
for  the  introduction  of  radical  methyl  into  other  compounds;  and  in  the 
arts,  in  the  manufacture  of  aniline  colors. 


Ethyl  Chloride. 

Hydrochloric  or  'muriatic  ether,  C2H5C1. — A  colorless,  mobile  liquid; 
boils  at  11°;  has  an  agreeable  odor;  burns  with  a  greenish  flame.  It  is 
obtained  by  passing  hydrochloric  acid  gas  through  ethylic  alcohol  to  satu- 
ration, and  distilling  over  the  water-bath.  It  is  used  in  medicine  in  alco- 
holic solution;  it  also  exists  in  tr.  ferri  chloridi. 


Ethyl  Bromide. 

Hydrobromic  ether,  C2H6Br. — A  colorless  liquid;  boils  at  40.7°;  has 
an  ethereal  odor;  a  taste  at  first  sweet,  afterward  disagreeable  and  burn- 
ing. Obtained  by  the  combined  action  of  phosphorus  and  bromine  on 
ethylic  alcohol.  Possesses  anaesthetic  properties. 


Ethyl  Iodide. 

Hydriodic  ether,  CaH6I. — This  compound,  which  is  of  considerable 
commercial  importance  since  the  introduction  of  the  aniline  industry,  and 
which  has  also  rendered  very  valuable  service  in  the  laboratory,  is  pre- 
pared by  placing  thirty-five  parts  of  absolute  alcohol  and  seven  parts  of 
phosphorus  in  a  vessel  surrounded  by  a  freezing  mixture,  and  gradually 
adding  thirty-two  parts  of  iodine;  when  the  action  has  ceased,  the  liquid 
is  decanted,  distilled  over  the  water-bath,  and  the  distillate  washed  and 
purified. 

It  is  a  colorless  liquid;  heavier  than  water;  boils  at  72.2°;  has  a  power- 
ful ethereal  odor,  and  becomes  brown  when  exposed  to  the  light.  It  burns 
with  difficulty. 

Similarly  constituted  chlorides,  bromides,  and  iodides  of  the  higher 
radicals  of  this  series  have  been  obtained;  they  resemble  those  described 
in  their  properties  and  methods  of  formation.  The  use  of  arnyl  chloride, 
C6HnCl,  as  an  anaesthetic,  has  been  suggested. 


MONOCHLOKMETHYL    CHLORIDE.  163 


PRODUCTS  OF  FURTHER  SUBSTITUTION. 

When  chlorine  is  allowed  to  act  upon  marsh-gas,  it  replaces  one  or 
more  atoms  of  hydrogen,  according  to  the  proportions  of  the  two  gases 
and  the  energy  of  the  reaction.  If  we  consider  rnarsh-gas  as  being  the 
hydride  of  the  radical  methyl,  the  first  of  these  products  is  the  simple 
methyl  chloride,  already  mentioned;  the  second,  the  chloride  of  a  radical 
obtained  from  methyl  by  the  substitution  of  one  atom  of  chlorine  for  one 
of  its  atoms  of  hydrogen,  CHaCla,  etc.  The  formation  of  these  products 
may  be  indicated  thus: 


v^^-j.    ,  ^*2  =H01  -|-CHgCl. 
CH4  +  2C12 = 2HC1 + CH2Cla. 
CH4+3C12=3HC1+CHC13. 
CH4  +  4C12=:4HC1+CC14. 

Considering  them   as  derivatives  of  marsh-gas,  methyl  hydride,  they 

PH  )  CH   i 

should  be  called:      rr3  f  —Methyl  hydride  =  marsh-gas.         p|  [•  =  Methyl 

chloride.  2™  !•   =  Monochlormethyl  chloride.  ^j  !•   =  Dichlor- 

PP1   ) 

methyl  chloride = chloroform.  p|  [•  =  Trichlormethyl  chloride  =  tetra- 

jhloride  of  carbon. 

Similar  products  are  formed  with  bromine  and  iodine. 

Monochlormethyl  Chloride. 

I  v. 

Methene  chloride — Methylene  chloride — Dichloromethane — CH2C1, 01. 
-By  some  chemists  considered  as  the  chloride  of  a  divalent  radical, 
(CHa)"  =  methylene,  whose  existence,  however,  in  this  compound  is  prob- 
lematical. 

It  is  obtained  by  the  action  of  chlorine  upon  methyl  chloride,  or  by 
shaking  an  alcoholic  solution  of  chloroform  with  powdered  zinc  and  a 
little  ammonium  hydrate,  the  nascent  hydrogen  thus  formed  separating 
a  portion  of  the  chlorine  as  hydrochloric  acid.  In  either  case  the  product 
must  be  purified. 

It  is  a  colorless,  oily  liquid;  boils  at  40° — 42°;  sp.  gr.,  1.36;  its  odor  is 
similar  to  that  of  chloroform.  It  is  very  slightly  soluble  in  water,  and  is 
not  inflammable. 

Under  the  names  bichloride  of  methylene  and  chloromethyl,  it  has 
been  used  as  a  substitute  for  chloroform  in  the  production  of  anaesthesia, 
and  the  hope  was  entertained  that  it  would  prove  the  safer  agent  of  the 
two — a  hope  which  subsequent  experience  has  not  justified.  In  the  three 
years  following  its  introduction  (1868-1871)  four  cases  of  death  from  its 
use  were  recorded. 


164  GENERAL    MEDICAL    CHEMISTRY. 


Dichlormethyl  Chloride. 

Methenyl  chloride — Formyl  chloride  —  Chloroform — Chlorofonmim 
(U.  S.,  Br.) — CHC12C1. — This  important  compound  was  discovered  in  1831, 
by  Dr.  Samuel  Guthrie,  of  Sackett'sf  Harbor,  N.  Y.,  and  at  about  the 
same  time  by  Liebig,  in  Germany,  and  by  Soubeiran,  in  France. 

It  is  obtained  by  heating  to  40°,  in  a  capacious  still,  thirty-five  to 
forty  litres  of  water,  adding  five  kilos  of  recently  slacked  lime  and  ten 
kilos  of  chloride  of  lime;  two  and  one-half  litres  of  alcohol  are  then  added, 
and  the  temperature  is  quickly  raised  until  the  product  begins  to  distil 
over,  when  the  fire  is  withdrawn,  the  action  continuing  of  itself  until  to- 
ward the  end,  when  heat  is  again  applied.  By  this  process  the  crude 
chloroform  of  the  dispensatory,  Chloroformum  venale  (U.  S.),  is  obtained. 
It  is  still  very  impure,  and,  to  purify  it,  it  is  first  shaken  with  sulphuric 
acid,  from  which  it  is  separated  by  decantation,  then  thoroughly  mixed 
with  alcohol  and  recently  ignited  potassium  carbonate,  the  mixture 
shaken,  and  redistilled  at  the  temperature  of  the  water-bath ;  the  distillate 
is  pure  chloroform. 

Chloroform  is  a  colorless,  volatile  liquid,  having  a  strong,  agreeable 
ethereal  odor,  and  a  sweet  taste.  It  is  heavier  than  water  (sp.  gr.  1.497) ; 
very  sparingly  soluble  in  water;  miscible  with  alcohol  and  ether  in  all 
proportions;  boils  at  60.8°.  It  ignites  with  difficulty,  but  may  be  burned 
from  a  cotton  wick,  giving  a  red,  smoky  flame,  bordered  with  green, 
which  gives  off  vapors  of  hydrochloric  acid.  It  is  a  good  solvent  for 
many  substances  insoluble  in  water — phosphorus,  iodine,  fats,  resins, 
caoutchouc,  gutta-percha,  and  the  alkaloids. 

Chloroform  is  not  acted  on  by  concentrated  sulphuric  acid,  except  by 
long  contact,  when  hydrochloric  acid  is  given  off.  Chlorine,  under  the 
influence  of  direct  sunlight,  converts  it  into  tetrachloride  of  carbon,  CC14, 
and  hydrochloric  acid.  It  is  not  attacked  by  the  alkalies  in  aqueous  so- 
lution; but  when  heated  with  them  in  alcoholic  solution,  it  is  decomposed 
with  formation  of  chloride  and  formiate  of  the  alkaline  metal.  If  a 
small  quantity  of  aniline  be  present  during  the  action  of  the  alcoholic 
solution  of  the  alkali  upon  chloroform,  isobenzonitril  is  formed,  and  may 
be  recognized  by  its  peculiar  odor.  Perfectly  pure  chloroform  is  not 
altered  by  exposure  to  light;  but  if  it  contain  compounds  of  nitrogen, 
even  in  very  minute  quantity  (derived  from  impurities  in  the  sulphuric 
acid  used  in  its  purification),  it  is  gradually  decomposed,  when  exposed 
to  direct  sunlight,  into  hydrochloric  acid,  chlorine,  and  other  substances. 

The  most  notable  property  of  chloroform  is  its  power  of  producing 
anaesthesia  when  its  vapor,  largely  diluted  with  air,  is  inhaled.  If  chlo- 
roform be  used  at  all  as  an  anaesthetic,  the  physician  should  satisfy  him- 
self of  its  purity  before  using  it.  The  substances  with  which  it  is  liable 
to  be  contaminated  are  alcohol,  aldehyde,  hydrochloric  acid,  and  methyl 
compounds.  Alcohol  may  be  detected,  if  present  in  large  quantity,  by 
the  low  specific  gravity  of  the  chloroform,  by  its  sinking  through  water 
in  opaque,  pearly  drops,  and  by  the  slow  separation  and  diminution  in 
volume  of  a  measured  quantity  of  chloroform  when  shaken  with  water. 
If  alcohol  be  present  in  small  quantity,  it  is  revealed  by  the  production  of 
a  green  color  when  the  impure  chloroform  is  shaken  with  ferrous  dinitro- 
sulphide  (obtained  by  acting  on  ferric  chloride  with  a  mixture  of  potas- 
sium nitrate  and  ammonium  hydrosulphide).  Chloroform  containing 
aldehyde  communicates  a  brown  color  to  liquor  potassre  heated  with  it. 


DICHLOKMETHYL    CHLORIDE.  165 

Chloroform  containing  hydrochloric  acid  reddens  blue  litmus  paper,  and 
causes  a  white  precipitate  in  an  aqueous  solution  of  silver  nitrate,  when 
shaken  with  it.  Probably  the  most  dangerous  contaminations  of  chloro- 
form are  certain  methylic  and  empyreumatic  compounds,  which,  if  im- 
properly prepared,  it  contains  in  small  quantities.  The  absence  of  these 
is  ascertained  by:  1st,  shaking  the  chloroform,  in  a  glass-stoppered  bot- 
tle, with  an  equal  volume  of  colorless  sulphuric  acid.  After  twenty-four 
hours  the  chloroform  (upper)  layer  should  be  perfectly  colorless,  and  the 
acid  layer  colorless  or  faintly  tinged  with  yellow;  2d,  evaporating  a  small 
quantity  spontaneously,  the  last  portions  should  have  no  pungent  odor, 
and  the  remaining  film  of  moisture  should  have  no  odor  or  taste  other 
than  those  of  chloroform. 

Toxicology. — The  action  of  chloroform  varies  as  it  is  taken  by  the 
•stomach  or  by  inhalation.  In  the  former  case,  owing  to  its  insolubility, 
but  little  is  absorbed,  and  the  principal  action  is  the  local  irritation  of 
the  mucous  surfaces.  Recovery  has  followed  a  dose  of  four  ounces,  and 
death  has  been  caused  by  one  drachm,  taken  into  the  stomach. 

Chloroform  vapor  acts  much  more  energetically,  and  seems  to  owe  its 
potency  for  evil  to  its  paralyzing  influence  upon  the  nerve-centres,  nota- 
bly upon  those  of  the  heart.  While  persons  suffering  from  heart  disease 
are  particularly  susceptible  to  the  paralyzing  effect  of  chloroform  vapor, 
there  are  several  cases  recorded  of  death  from  the  inhalation  of  small 
quantities,  properly  diluted,  in  which  no  heart-lesion  was  found  upon  a 
post-mortem  examination. 

Chloroform  is  apparently  not  altered  in  the  system,  and  is  eliminated 
with  the  expired  air. 

There  is  no  chemical  antidote  to  chloroform.  When  it  has  been  swal- 
lowed, the  stomach-pump  and  emetics  are  indicated;  when  taken  by  inha- 
lation, a  free  circulation  of  air  should  be  established  about  the  face; 
artificial  respiration  and  the  application  of  the  induced  current  to  the  sides 
of  the  neck  should  be  resorted  to. 

The  nature  of  the  poison  is  usually  revealed  at  the  autopsy  by  its 
peculiar  odor,  which  is  most  noticeable  on  opening  the  cranial  and  thora- 
cic cavities.  In  a  toxicological  analysis,  chloroform  is  to  be  sought  for 
especially  in  the  lungs  and  blood.  These  are  placed  in  a  flask,  if  acid, 
neutralized  with  sodium  carbonate,  and  subjected  to  distillation  at  the 
temperature  of  the  water-bath.  The  vapors  are  passed  through  a  tube  of 
difficultly  fusible  glass;  at  first  the  tube  is  heated  to  redness  for  about  an 
inch  of  its  length,  and  a  piece  of  filter-paper,  moistened  with  starch  paste 
and  with  a  solution  of  potassium  iodide,  is  held  at  the  orifice;  if  chloro- 
form vapor  be  present,  it  is  decomposed  into  carbon,  hydrochloric  acid, 
and  free  chlorine,  and  the  last-named  turns  the  paper  blue  by  the  libera- 
tion of  iodine  (the  color  is  afterward  bleached  if  chlorine  be  present  in 
large  quantity).  The  escaping  vapor  is  then  allowed  to  bubble  through 
a  solution  of  silver  nitrate  acidulated  with  nitric  acid,  when,  if  chloroform 
be  present,  a  white  precipitate,  soluble  in  ammonia,  is  formed.  Finally, 
the  tube  is  allowed  to  cool,  and  the  distillate  collected  in  a  pointed  tube; 
if  chloroform  be  present  in  considerable  quantities  it  collects  in  a  distinct 
layer  or  in  drops  at  the  lower,  pointed  end  of  the  receiver.  The  superna- 
tant, watery  liquid  is  drawn  off  with  a  pipette;  the  drops  of  chloroform, 
whose  odor  may  be  recognized,  dissolved  in  a  small  quantity  of  alcohol, 
and  to  this  solution  a  little  alcoholic  solution  of  potassium  hydrate  and 
two  or  three  drops  of  aniline  are  added,  and  the  mixture  gently  warmed; 
if  chloroform  be  present,  even  in  small  quantity  (one  part  to  five  thou- 


166  GENERAL    MEDICAL    CHEMISTRY. 

sand  parts  alcohol)  the  peculiar,  disagreeable  odor  of  isobenzonitril  is  ob- 
served (Hofmann). 

Tetrachloride  of  Carbon,  CC14 — the  product  of  the  most  com- 
plete substitution  of  chlorine  for  hydrogen  in  marsh-gas.  It  is  formed  by 
the  prolonged  action  of  chlorine  upon  methyl  chloride,  or  upon  chloroform, 
under  the  influence  of  direct  sunlight,  r"  More  quickly  by  passing  chlorine, 
charged  with  vapor  of  carbon  disulphide,  through  a  red-hot  tube,  and 
purifying  the  product. 

It  is  a  colorless,  oily  liquid,  insoluble  in  water,  soluble  in  alcohol  and 
in  ether;  haying  an  agreeable  ethereal  odor  ;  sp.  gr.  1.56;  boiling  at  78°. 
Its  vapor,  when  heated  to  redness,  either  alone  or  mixed  with  hydrogen, 
is  decomposed,  yielding  a  mixture  of  dichloride,  C2C14,  trichloride,  C2C16,. 
and  free  chlorine. 

Its  action  upon  the  economy  is  similar  to  that  of  chloroform.  It  is 
known  in  pharmacy  as  chlorocarbon. 


Dibromomethyl  Bromide. 

Methenyl  bromide — Formyl  bromide — Bromoform — CHBr2,  Br. — is 
prepared  by  gradually  adding  bromine  to  a  cold  solution  of  potassium 
hydrate,  until  the  liquid  begins  to  be  colored,  and  rectifying  over  calcium 
chloride. 

A  colorless  liquid  of  sp.  gr.  2.13,  having  an  aromatic  odor  and  a  sweet 
taste,  less  volatile  than  chloroform,  boils  at  150° — 152°,  solidifies  at  — 9°, 
sparingly  soluble  in  water,  to  which  it  communicates  its  taste  and  odor, 
soluble  in  alcohol  and  ether.  When  boiled  with  alcoholic  potash,  it 
undergoes  a  decomposition  similar  to  that  of  chloroform.  It  burns  with 
difficulty,  and  is  decomposed  at  a  red  heat. 

Its  physiological  action  is  similar  to  that  of  chloroform.  It  often 
exists  as  an  impurity  in  commercial  bromine,  accompanied  by  carbon 
tetrabromide,  CBr4. 


Diiodomethyl  Iodide. 

Methenyl  iodide — Formyl  iodide — lodoform — CHIaI. — Formed,  like 
chloroform  and  bromoform,  by  the  combined  action  of  potash  and  the 
halogen  upon  alcohol;  it  is  also  produced  by  the  action  of  iodine  upon  a 
great  number  of  organic  substances,  and  is  usually  prepared  by  heating 
to  60° — 80°  a  mixture  of  three  parts  alkaline  carbonate,  ten  parts  water, 
one  part  iodine  and  one  part  ethylic  alcohol,  and  purifying  the  product 
by  recrystallization  from  alcohol. 

lodoform  differs  widely  from  its  chlorine  and  bromine  congeners  both 
in  appearance  and  properties.  It  is  a  solid,  crystallizing  in  yellow  hexa- 
gonal plates,  which  melt  at  115° — 120°.  It  may  be  sublimed,  a  portion 
being  decomposed.  It  is  insoluble  in  water,  acids,  and  alkaline  solutions;, 
soluble  in  alcohol,  ether,  carbon  disulphide,  and  the  fatty  and  essential 
oils;  the  solutions,  when  exposed  to  the  light,  undergo  decomposition 
and  assume  a  violet-red  color.  It  has  a  sweet  taste  and  a  peculiar,  pene- 
trating odor,  resembling,  when  the  vapor  is  largely  diluted  with  air,  that 
of  saffron.  When  heated  with  potash,  a  portion  is  decomposed  into 
formiate  and  iodide,  while  another  portion  is  carried  off  unaltered  with 
the  aqueous  vapor.  It  contains  96.7$  of  its  weight  of  iodine. 


MONOATOMIC  ALCOHOLS.  167 

It  possesses  anaesthetic  powers,  less  active  than  those  of  chloroform 
and  bromoform,  and  principally  localized  to  the  sphincters.  Experiments 
upon  animals  show  that  it  is  poisonous  in  smaller  doses  than  iodine. 


Diehlormethyl  Iodide. 

Chloroiodoform,  CHC12,I — is  formed  when  iodoform  is  heated  with 
mercuric  chloride;  a  dark  red  liquid  distils,  which,  when  treated  with 
potash  and  redistilled,  yields  a  yellowish  liquid,  having  an  aromatic  odor 
and  a  sweetish  taste;  sp.  gr.  1.96. 


Dibromomethyl  Iodide. 

JBromoiodoform,  CHBr2l — is  a  colorless  liquid,  solidifying  at  0°,  very 
volatile,  sweet  in  taste,  having  a  penetrating  odor;  obtained  by  the 
action  of  bromine  upon  iodoform. 


Chlorinated  Derivatives  of  Ethyl  Chloride. 

By  the  action  of  chlorine  upon  ethyl  chloride,  a  progressive  substitu- 
tion of  atoms  of  chlorine  for  atoms  of  hydrogen  occurs,  with  formation  of 
the  following  substances : 

Monochlorethyl  chloride C2H4C1,C1 boils  at    64° 

Dichlorethyl  chloride C2H3C12,C1 ....  boils  at    75° 

Trichlorethyl  chloride C2H2C13,C1. . .  .boils  at  102° 

Tetrachlorethyl  chloride C2HC14,C1  . . .  .boils  at  146° 

Carbon  trichloride C2C16 boils  at  182° 


The  first  of  these  is  isomeric  with  "  Dutch  liquid  "  (see  page  229)  and 
possesses  anaesthetic  powers.  A  product  containing  the  three  following, 
in  varying  quantities,  has  been  used  as  an  anaesthetic  under  the  names 
cether  ancestheticus  Arani.  Carbon  trichloride,  also  called  sesquichloride 
or  perMoride  of  carbon,  is  obtained  by  the  action  of  chlorine  upon  ethyl 
chloride  or  upon  Dutch  liquid,  under  the  influence  of  sunlight.  It  forms 
colorless,  transparent  crystals,  almost  tasteless,  having  an  odor  resembling 
that  of  camphor;  hard,  insoluble  in  water,  soluble  in  alcohol  and  in  ether, 
fusing  at  160°,  volatile  at  182°.  Has  been  used  medicinally  as  a  local 
anaesthetic,  and  in  cholera. 


MONOATOMIC  ALCOHOLS. 

Series  CnH2n+2O. 

This  series  consists  of  the  hydrates  of  the  radicals  CnH2n  +1,  derived 
from  the  saturated  hydrocarbons  (see  pp.  149,  157),  and  contains  some  of 
the  most  important  of  the  organic  compounds.  The  following  is  a  list  of 
the  terms  of  the  series  which  have  been  studied,  and  their  prominent 
physical  properties. 


168 


GENERAL    MEDICAL    CHEMISTKY. 


ALCOHOLS — SERIES  CnH2n+2O. 


Name. 

Epipirieal 
formula. 

Typica 
forjnuk 

[ 

t. 

Fusing- 
point. 

Boiling- 
point. 

Specific 
gravity. 

Methyl  hydrate  

CH4O 

CH3) 

o 

66°  5 

0.814 

Ethyl  hydrate               .... 

C2H6O 

H 
C2H5 

o 

78°  3 

0  8095 

C3H8O 

H 
C3H7 

o 

96°.7 

0  820 

Butyl  hydrate  
Amyl  hydrate  

C<H1(10 
C5H12O 

H 
C4H9 
Hi 

CsHn 

0 
-0 

20° 

114°.  7 
132° 

0.817 

Hexyl  hydrate       .          .   . 

C6H14O 

C6H13 

-0 

150° 

0  820 

C7H16O 

H 
C7Hi6 

o 

168° 

Octyl  hydrate    

C8H18O 

H 
C8H17 

o 

186° 

Nonyl  hydrate  

C9H20O 

H 
C8H19 

to 

204° 

Decyl  hydrate   ....        .   . 

H 

CioH21 

.0 

Cetyl  hydrate  

Ci6H34O 

H  j 

c16H33  ; 

o 

49° 

C27H66O 

H  j 

Ca7H56  i 

•  O 

79° 

Myricyl  hydrate  

CaoHeaO 

Hj 

c30H61  ; 

o 

85° 

Hj 

Methyl  Hydrate. 

Methylic  alcohol —  Carbinol — Pyroxylic  spirit —  Wood  spirit — CH3HO. 
— Does  not  exist  in  nature,  may  be  obtained  from  marsh-gas,  methyl 
hydride,  by  first  converting  it  into  the  iodide,  which  is  then  acted  upon 
by  potassium  hydrate: 

CH3I + KHO  =  KI  +  CH3HO. 

It  is  obtained  in  the  arts  by  the  destructive  distillation  of  wood  (whence 
the  name,  from  /u,e'0v,  wine,  and  v\rj,  wood).  When  wood  is  decomposed  at 
a  high  temperature  in  closed  vessels,  there  are  formed  charcoal,  gaseous 
and  tarry  products,  and  an  aqueous  fluid  which  is  known  as  crude  wood 
vinegar,  and  contains  a  number  of  substances,  notably  acetic  acid  and 
methylic  alcohol.  The  crude  vinegar  is  separated  by  decantation  from 
the  tarry  products  and  redistilled,  the  first  tenth  is  collected,  treated  with 
quicklime  and  again  distilled  ;  the  distillate  treated  with  dilute  sulphuric 
acid,  decanted,  and  again  distilled  from  quicklime;  the  product,  still  quite 
impure,  is  the  wood  alcohol,  wood  naphtha,  and  pyroxylic  spirit  of  com- 
merce. It  may  be  further  purified  by  causing  it  to  combine  with  calcium 
chloride,  decomposing  the  crystalline  compound  formed  by  the  addition 
of  water,  and  rectifying  from  quicklime ;  all  these  distillations  are  carried 


ETHYL    HYDRATE.  169 

on  at  the  temperature  of  the  water-bath.  The  pure  hydrate  is  obtained 
by  forming  a  crystalline  compound,  such  as  methyl  oxalate,  which  is 
purified,  decomposed,  and  the  product  rectified  until  the  boiling-point  is 
constant  at  66.5°. 

Pure  methyl  alcohol  is  a  colorless  liquid,  having  an  ethereal  and  alco- 
holic odor,  and  a  sharp,  burning  taste;  sp.  gr.  0.814  at  0°;  boils  at  66.5°, 
bumping  so  as  to  render  its  distillation  difficult.  It  burns  with  a  pale 
flame,  giving  less  heat  than  that  of  ethylic  alcohol.  It  mixes  with  water, 
alcohol,  and  ether  in  all  proportions;  is  a  good  solvent  of  resinous  sub- 
stances, and  also  dissolves  sulphur,  phosphorus,  potash,  and  soda,  the 
solutions  of  the  last-named  substances  becoming  colored  on  contact  with 
air. 

Methyl  hydrate  is  not  affected  by  exposure  to  air  under  ordinary  cir- 
cumstances, but  in  the  presence  of  platinum-black  it  is  oxidized,  with  for- 
mation of  the  corresponding  aldehyde  and  acid,  formic  acid. 

Nitric  acid,  aided  by  heat,  decomposes  it  with  formation  of  nitrous 
fumes,  formic  acid,  and  methyl  nitrate.  When  heated  with  nitric  acid  and 
silver  nitrate,  it  produces  no  fulminate.  Sulphuric  acid  acts  upon  methyl 
alcohol  as  it  does  upon  ethyl  hydrate  (q.v.).  The  organic  acids  pro- 
duce ethers  with  methyl  alcohol,  as  they  do  with  all  the  members  of  the 
series. 

It   dissolves  potassium  and  sodium  with  liberation  of  hydrogen,  and 

CH   ) 
th@  formation   of  oxides  of  methyl  and  potassium  or  sodium;      ^  j-  O  or 

OH"   -\ 
-XT  3  [  O.     With  baryta  and  with  calcium  chloride  it  forms  crystallized 

compounds.  With  hydrochloric  acid,  under  the  influence  of  the  galvanic 
current,  it  forms  an  oily  substance  having  the  composition  C2H3C1O. 

Uses. — It  is  used  in  the  arts  in  the  preparation  of  varnishes;  as  a 
solvent  in  many  processes,  and  in  the  manufacture  of  aniline  dyes. 

Methylated  spirit  is  ethyl  alcohol  containing  sufficient  wood  spirit  to 
render  it  unfit  for  the  manufacture  of  ardent  spirits  by  reason  of  the  dis- 
gusting odor  and  taste  which  crude  wood  alcohol  owes  to  certain  empy- 
reumatic  products  which  it  contains.  Spirits  so  treated  are  not  subject 
to  the  heavy  duties  imposed  upon  ordinary  alcohol,  and  are,  therefor, 
largely  used  in  the  arts  and  for  the  preservation  of  anatomical  prepara- 
tions; it  contains  one-ninth  of  its  bulk  of  wood  naphtha. 

W^hen  taken  internallv  it  produces  the  same  effects  as  does  ordinary 
alcohol;  it  seems,  however,  to  be  rather  more  active.  Its  use  as  a  thera- 
peutic agent  has  been  suggested. 


Ethyl  Hydrate. 

Ethylic  alcohol — Methyl  carbinol —  Vinic  alcohol — Alcohol — Spirits 
of  wine — C2H5HO. — Liquids  containing  alcohol  were  known  and  were 
prepared  for  use  as  beverages  in  remote  antiquity.  It  was  only  in  the 
middle  ages,  however,  that  the  alchemists  separated  alcohol,  still  con- 
taining water,  from  wine,  whence  it  received  the  name,  still  used  in  speak- 
ing of  diluted  alcohol,  of  spirits  of  wine.  Saussure  was  the  first  to  de- 
termine its  composition. 

Alcohol  does  not  exist  in  nature,  but  is  produced  in  a  number  of  re- 
actions. One  method  of  its  formation,  which  has  an  historical  interest  as 


170  GENERAL    MEDICAL    CHEMISTRY. 

that  by  which  its  constitution  was  determined,  is  by  the  formation  of  sul 
phovinic  acid  and  the  subsequent  decomposition  of  this  by  water: 


Sulphuric    Ethylene  Sulphovinic 

acid.'  '    .  acid. 

S04HC2H5  +  H20  =  S04H2  +  C2H5OH 

Sulphovinic         Water.     Sulphuric  Alcohol. 

acid.  acid. 

The  sources  from  which  alcohol  and  alcoholic  liquids  are  industrially 
obtained  are  always  vegetable  substances,  rich  in  starch  or  in  glucose,  by 
far  the  greater  proportion  being  obtained  from  starchy  materials. 

The  manufacture  of  alcohol  from  this  source  consists  of  three  distinct 
processes:  1st,  the  conversion  of  starch  into  sugar;  3d,  the  fermentation 
of  the  saccharine  liquid;  3d,  the  separation,  by  distillation,  of  the  alcohol 
formed  by  fermentation. 

The  raw  materials  for  the  first  process  are  malt  and  some  substance 
(grain,  potatoes,  rice,  corn,  etc.)  containing  starch.  Malt  is  barley  which 
has  been  allowed  to  germinate,  and,  at  the  proper  stage  of  germination, 
roasted.  During  this  growth  there  is  developed  in  the  barley  a  peculiar 
nitrogenous  principle  called  diastase.  The  starchy  material  is  mixed 
with  a  suitable  quantity  of  malt  and  water,  and  the  mass  maintained  at  a 
temperature  of  65°  —  70°  for  two  to  three  hours,  during  which  the  dias- 
tase rapidly  converts  the  starch  into  dextrine,  and  this  in  turn  into  glu- 
cose. The  saccharine  fluid,  or  wort,  obtained  in  the  first  process,  is  drawn 
off,  cooled,  and  yeast  is  added.  As  a  result  of  the  growth  of  the  yeast- 
plant,  a  complicated  series  of  chemical  changes  take  place,  the  principal 
one  of  which  is  the  splitting  up  of  the  glucose  into  carbon  dioxide  and 
alcohol: 

C6H1206=2C2H5OH+2C02 

Glucose.  Alcohol.  Carbon 

dioxide. 

There  are  formed  at  the  same  time  small  quantities  of  glycerine,  succinic 
acid,  and  propyl,  butyl,  and  amyl  alcohols. 

An  aqueous  fluid  is  thus  obtained  which  contains  from  three  to  fifteen 
per  cent,  of  alcohol;  this  is  then  separated  by  the  third  process,  that  of 
distillation  or  rectification.  The  apparatus  used  for  this  purpose  has  been 
so  far  perfected  that  by  a  single  distillation  an  alcohol  of  90  —  95  per  cent, 
can  be  obtained. 

In  some  cases  alcohol  is  prepared  from  fluids  rich  in  glucose,  such  as 
grape-juice,  molasses,  syrup,  etc.  ;  in  such  cases  the  first  process  becomes 
unnecessary. 

Commercial  alcohol  always  contains  water,  and  when  pure  or  absolute. 
alcohol  is  required,  the  commercial  product  must  be  mixed  with  some  hy- 
groscopic solid  substance,  such  as  quicklime,  from  which  it  is  distilled 
after  having  remained  in  contact  twenty-four  hours. 

Alcohol  is  a  thin,  colorless,  transparent  liquid,  having  a  spirituous  odor, 
and  a  sharp,  burning  taste;  sp.  gr.  0.8095  at  0°,  0.7939  at  15°;  it  boils  at 
78.5°,  and  has  not  been  solidified;  at  temperatures  below  —90°  it  is  vis- 
cous. It  mixes  with  water  in  all  proportions,  the  union  being  attended  by 
elevation  in  temperature  and  contraction  in  volume  (after  cooling  to  the 
original  temperature).  If  52.3  volumes  of  alcohol  be  mixed  with  47.07 
of  water,  at  15°,  the  mixture  occupies  96.35  volumes,  the  maximum  of 


ETHYL    HYDRATE.  171 

contraction.  It  also  attracts  moisture  from  the  air  to  such  a  degree  that 
absolute  alcohol  only  remains  such  for  a  very  short  time  after  its  prepara- 
tion. It  is  to  this  power  of  attracting  water  that  alcohol  owes  its  preserv- 
ative power  for  animal  substances,  and  probably  also  its  power  of  coagula- 
ting albuminoid  substances.  It  is  a  very  useful  solvent,  dissolving  a  number 
of  gases,  most  of  the  mineral  and  organic  acids  and  alkalies,  most  of  the 
chlorides  and  carbonates,  some  of  the  nitrates,  all  the  sulphates,  essences, 
and  resins.  Most  of  the  varnishes  consist  of  alcoholic  solutions  of  resi- 
nous  materials.  Alcoholic  solutions  of  fixed  medicinal  substances  are 
called  tinctures'  those  of  volatile  principles,  spirits. 

The  action  of  oxygen  upon  alcohol  varies  according  to  the  conditions. 
Under  the  influence  of  energetic  oxidants,  such  as  chromic  acid,  or,  when 
alcohol  is  burned  in  the  air,  the  oxidation  is  rapid  and  complete,  and  is  at- 
tended by  the  extrication  of  much  heat  and  the  formation  of  carbon  di- 
oxide and  water: 

C2H6O+302=2CO2+3H20. 

Mixtures  of  air  and  vapor  of  alcohol  explode  upon  contact  with  flame.  If 
a  less  active  oxidant  be  used,  such  as  platinum-black,  or  by  the  action  of 
atmospheric  oxygen  at  low  temperatures,  a  simple  oxidation  of  the  alco- 
holic  radical  takes  place,  with  formation  of  acetic  acid: 

C0H 


a  reaction  which  is  utilized  in  the  manufacture  of  acetic  acid  and  vinegar.. 
If  the  oxidation  be  still  further  limited,  aldehyde  is  formed : 

2C2H60  +  Oa = 2C2H40  +  2H2O. 

If  vapor  of  alcohol  be  passed  through  a  tube  filled  with  platinum  sponge- 
and  heated  to  redness,  or  if  a  coil  of  heated  platinum  wire  be  introduced 
into  an  atmosphere  of  alcohol  vapor,  the  products  of  oxidation  are  quite 
numerous;  among  them  are  water,  ethylene,  aldehyde,  acetylene,  carbon 
monoxide,  and  acetal.  Heated  platinum  wire  introduced  into  vapor  of 
alcohol  continues  to  glow  by  the  heat  resulting  from  the  oxidation,  a  fact 
which  has  been  utilized  in  Doebereiner's  nameless  lamp,  and  in  the  ther- 
mocautery  recently  introduced  in  surgical  practice. 

Chlorine  and  bromine  act  energetically  upon  alcohol,  producing  a 
number  of  chlorinated  and  brominated  derivatives,  the  final  products  be- 
ing chloral  and  bromal  (q.  v.).  If  the  action  of  chlorine  be  moderated,, 
aldehyde  and  hydrochloric  acid  are  first  produced.  Iodine  acts  quite 
slowly  in  the  cold,  but  old  solutions  of  iodine  in  alcohol  (tr.  iodine)  are 
found  to  contain  hydriodic  acid,  ethyl  iodide,  and  other  imperfectly 
studied  products.  In  the  presence  of  an  alkali,  iodine  acts  upon  alcohol 
to  produce  iodoform. 

Potassium  and  sodium  dissolve  in  alcohol  with  evolution  of  hydrogen; 
upon  cooling,  a  white  solid  crystallizes,  which  is  the  double  oxide  of  ethyl 
and  the  alkaline  metal: 


!Vo 

H;  u 

Water  or  hydrogen 
oxide. 

Klo 

H|C 

Potassium  hydrate 
or  oxide  of  hydro- 
gen and  potassium. 

°'HH}° 

Ethyl  hydrate  or  ox- 
ide of  hydrogen 
and  ethyl. 

?5|o 

Oxide  of  ethyl  and 
potassium. 

172  GENERAL    MEDICAL    CHEMISTRY. 

These  compounds,  on  contact  with  water,  are  decomposed,  with  re- 
generation of  alcohol  and  formation  of  the  alkaline  hydrate. 

Nitric  acid,  aided  by  a  gentle  heat,  acts  violently  upon  alcohol,  pro- 
ducing nitrous  ether,  brown  fumes,  and  products  of  oxidation.  For  the 
.action  of  other  acids  uport-ajcohol  see  the  corresponding  ethers. 

The  hydrates  of  the  alkaline  metals  dissolve  in  alcohol,  but  react  up- 
on it  slowly;  the  solution  turns  brown  and  contains  an  acetate. 

If  alcohol  be  gently  heated  with  nitric  acid  and  the  nitrate  of  silver  or 
•of  mercury,  a  gray  precipitate  falls,  which  is  silver  or  mercury  fulminate. 
Uses. — Alcohol  is  used  in  a  great  number  of  processes,  in  the  arts, 
;and  in  pharmacy,  principally  as  a  solvent,  but  also  as  a  starting-point  in 
the  manufacture  of  a  number  of  substances,  as  vinegar,  chloral,  chloro- 
form, and  ether;  as  a  menstruum  in  the  preparation  of  tinctures  and 
.spirits;  and  to  a  certain  extent  as  a  fuel,  when  a  hot  and  smokeless  flame 
is  desired. 

It  occurs  in  commerce,  and  is  used  pharmaceutically  in  different  de- 
grees of  concentration. 

Absolute  alcohol  is  pure  alcohol,  C2H6O,  prepared  as  desired  by  the 
method  given  above.  It  is  not  purchasable;  the  so-called  absolute  alco- 
hol of  the  shops  is  rarely  stronger  than  ninety-eight  per  cent. 

Alcohol  fortius  (U.  S.) — stronger  alcohol,  is  of  sp.  gr.  0.817,  and  con- 
tains ninety-two  per  cent,  alcohol. 

Alcohol  (U.  S.)< — sp.  gr.  0.835  —  Spiritus  rectificatus  (Br.) — sp.  gr. 
O.838 — is  the  ordinary  rectified  spirit,  used  for  most  purposes  in  the  arts; 
it  contains  eighty-five  per  cent,  alcohol. 

Alcohol  dilutum  (U.  S.) — sp.  gr.  0.941  =  Spiritus  tenuior  (Br.) — sp. 
gr.  0.920 — used  for  the  preparation  of  tinctures.  It  contains  thirty-nine 
per  cent.,  U.  S.,  or  forty-nine  per  cent.,  Br.,  of  alcohol.  The  British 
officinal  is  of  the  same  strength  as  the  proof  spirit  of  commerce. 

Physiological  action. — In  a  concentrated  form,  alcohol  exerts  a  de- 
hydrating action  upon  animal  tissues  with  which  it  comes  in  contact; 
causing  coagulation  of  the  albuminoid  constituents.  When  diluted, 
ethylic  alcohol  may  be  a  food,  a  medicine,  or  a  poison,  according  to  the 
close  and  the  condition  of  the  person  taking  it,  AVhen  taken  in  excessive 
doses,  or  in  large  doses  for  a  long  time,  it  produces  the  symptoms  and 
lesions  characteristic  of  pure  alcoholism,  acute  or  chronic,  modified  or 
aggravated  by  those  produced  by  other  substances,  such  as  amyl  alcohol, 
which  accompany  it  in  the  alcoholic  fluids  used  as  beverages.  Taken  in 
moderate  quantities,  with  food,  it  aids  digestion  and  produces  a  sense  of 
comfort  and  exhilaration.  As  a  medicine  it  is  the  most  valuable  of 
stimulants. 

Much  has  been  written  concerning  the  value  of  alcohol  as  a  food.  If 
it  have  any  value  as  such,  it  is  as  a  producer  of  heat  and  force  by  its  ox- 
idation in  the  body;  experiments  made  in  the  interest  of  teetotalism  have 
failed  to  show  that  more  than  a  small  percentage  (sixteen  per  cent,  in 
twenty-four  hours)  of  medium  doses  of  alcohol  ingested  are  eliminated  by 
all  channels;  the  remainder,  therefor,  disappears  in  the  body,  as  the  idea 
that  it  can  there  "  accumulate  "  is  entirely  untenable.  That  some  part 
should  be  eliminated  unchanged  is  to  be  expected  from  the  rapid  diffusion 
and  the  high  volatility  of  alcohol. 

On  the  other  hand,  if  alcohol  be  oxidized  in  the  body,  we  should  ex- 
pect, in  the  absence  of  violent  muscular  exercise,  an  increase  in  tempera- 
ture, and  the  appearance  in  the  excreta  of  some  product  of  oxidation  of 
.alcohol,  aldehyde,  acetic  acid,  carbon  dioxide,  or  water,  while  the  elimi- 


ETHYL    HYDRATE.  17$ 

nation  of  nitrogenous  excreta,  urea,  etc.,  would  remain  unaltered  or  be- 
diminished.  While  there  is  no  doubt  that  excessive  doses  of  alcohol  pro- 
duce a  diminution  of  body  temperature,  the  experimental  evidence  con- 
cerning the  action  in  this  direction  of  moderate  doses  is  conflicting  and 
incomplete. 

Of  the  products  of  oxidation,  aldehyde  has  not  been  detected  in  the 
excreta,  and  acetic  acid  only  in  the  intestinal  canal.  The  elimination  of 
carbonic  acid,  as  such,  does  not  seem  to  be  increased,  although  positive 
information  upon  this  point  is  wanting.  If  acetic  acid  be  produced,  this 
would  form  an  acetate,  which  in  turn  would  be  oxidized  to  a  carbonate, 
and  eliminated  as  such  by  the  urine.  The  elimination  of  water  under  the 
influence  of  large  doses  of  alcohol  is  greater  than  at  other  times,  but 
whether  this  water  is  produced  by  the  oxidation  of  the  hydrogen  of  the 
alcohol,  or  is  removed  from  the  tissues  by  its  dehydrating  action,  is  an 
open  question. 

While  physiological  experiment  yields  only  uncertain  evidence,  the- 
experience  of  arctic  travellers  and  others  shows  that  the  use  of  alcohol 
tends  to  diminish  rather  than  increase  the  capacity  to  withstand  cold. 
The  experience  of  athletes  and  of  military  commanders  is  that  intense 
and  prolonged  muscular  exertion  can  be  best  performed  without  the  use 
of  alcohol.  The  experience  of  most  literary  men  is  that  long-continued 
mental  activity  is  more  difficult  with  than  without  alcohol. 

In  cases  of  acute  poisoning  by  alcohol,  the  stomach-pump  and  catheter 
should  be  used  as  early  as  possible.  A  plentiful  supply  of  air,  the  cold 
douche,  and  strong  coffee  are  indicated. 

Analysis. — The  presence,  of  alcohol  may  be  detected  by  the  following- 
reactions,  none  of  which,  taken  alone,  is,  however,  characteristic  of  alcohol 
under  all  circumstances. 

First. — If  a  solution  containing  alcohol  be  heated  with  a  small  quan- 
tity of  solution  of  potassium  dichromate  and  sulphuric  acid,  the  liquid 
assumes  an  emerald  green  color,  and,  if  the  quantity  of  alcohol  be  not- 
too  small,  the  peculiar  fruity  odor  of  aldehyde  is  observed.  The  green, 
color  is  produced  under  like  circumstances  by  many  reducing  agents. 

Second. — If  an  alcoholic  liquid  be  warmed  and  treated  with  a  few 
drops  of  potassium  hydrate  solution  and  a  small  quantity  of  iodine,  a  yel- 
low, crystalline  precipitate  of  iodoform  is  produced,  either  immediately 
or  after  a  time.  Many  other  organic  substances  produce  iodoform  under 
similar  conditions. 

Third. — If  nitric  acid  be  added  to  a  liquid  containing  alcohol,  nitrous 
ether,  recognizable  by  its  odor,  is  given  off  ;  if  a  solution  of  mercurous 
nitrate  with  excess  of  acid  be  then  added,  and  the  mixture  heated,  a 
further  evolution  of  nitrous  ether  occurs,  and  a  yellowish-gray  deposit  of 
fulminating  mercury  is  formed,  which  may  be  collected,  washed,  dried, 
and  exploded.  This  reaction  is  well  adapted  to  detecting  ethylic  in  me- 
thylic  alcohol,  as  the  latter  does  not  form  a  fulminate. 

Fourth. — Alcohol  may  be  detected  in  chloroform  by  shaking  it  with 
a  fragment  of  dry  potassium  hydrate,  removing  the  potash,  and  shaking 
the  chloroform  with  an  equal  volume  of  solution  of  cupric  sulphate;  a 
blue  precipitate  is  formed  if  the  chloroform  contained  alcohol. 

Fifth. — If  an  alcoholic  liquid  be  heated  for  a  few  moments  with  sulphuric 
acid,  diluted  with  water  and  distilled,  the  distillate,  on  treatment  with  sul- 
phuric acid  and  potassium  permanganate,  and  afterward  with  sodium 
hyposulphite,  yields  aldehyde,  which  may  be  recognized  by  the  produc- 
tion of  a  violet  color  on  the  addition  of  a  dilute  solution  of  fuchsine. 


174 


GENERAL    MEDICAL    CHEMISTRY. 


The  quantity  of  alcohol  in  an  alcoholic  liquid  is  usually  determined  by 
observing  the  specific  gravity.  If  the  liquid  contain  a  large  quantity  of 
alcohol  and  little  or  no  solid  matter,  as  in  the  case  of  the  alcohols  of  com- 
merce, this  is  done  directly;  if,  however,  the  liquid  hold  solid  matters  in 
solution,  as  in  the  case  of  wines  and  spirits  containing  sugar,  a  measured 
volume  of  the  liquid  is  distilled  until  the  alcohol  is  all  driven  into  the  dis- 
tillate, whose  specific  gravity  is  then  determined.  The  following  table 
indicates  the  percentage  of  alcohol  in  mixtures  of  water  and  alcohol  of 
different  specific  gravity,  at  60°  F.  =  15.5°  C.: 


Alcohol 
per  cent. 

II     - 

Specific           Alcohol 
gravity.     1  1    per  cent. 

1  . 

Specific 
gravity. 

Alcohol 
per  cent. 

Specific 
gravity. 

Alcohol 
per  cent. 

Specific 
gravity. 

0 

1.0000 

I 
25 

0.9652 

51 

0.9160 

76 

0.8581 

0.5 

9991 

26 

9638 

52 

9135 

77 

8557 

1 

9981 

27 

9623 

53 

9113 

78 

8533 

2 

9965 

28 

9609 

54 

9090 

79 

8508 

3 

9947 

29 

9593 

55 

9069 

80 

8483 

4 

9930 

30 

9578 

56 

9047 

81 

8459 

5 

9914 

31 

9560 

57 

9025 

82 

8434 

6 

9898 

32 

9544 

58 

9001 

83 

8408 

7 

9884 

33 

9528 

59 

8979 

84 

8382 

8 

9869 

34 

9511 

60 

8956 

85 

8357 

9 

9855 

35 

9490 

61 

8932 

86 

8331 

10 

9841 

36 

9470 

62 

8908 

87 

8305 

11 

9828 

37 

9452 

63 

8886 

88 

8279 

12 

9815 

38 

9434 

64 

8863 

89 

8254 

13 

9802 

39 

9416 

65 

8840 

90 

8228 

14 

9789 

40 

9396 

66 

8816 

91 

8199 

15 

9778 

41 

9376 

67 

8793 

92 

8172 

16 

9766 

42 

9356 

68 

8769 

93 

8145 

17 

9753 

43 

9335 

69 

8745 

94 

8118 

18 

9741 

44 

9314 

70 

8721 

95 

8089 

19 

9728 

45 

9292 

71 

8696 

96 

8061 

20 

9716 

46 

9270 

72 

8672 

97 

8031 

21 

9704 

47 

9249 

73 

8649 

98 

8001 

23 

9691 

48 

9228 

74 

8625 

99 

7969 

23 

9678 

49 

9206 

75 

8603 

100 

7938 

24 

9665 

50 

9184 

Alcoholic  Beverages. 

The  variety  of  beverages  in  whose  preparation  alcoholic  fermentation 
plays  an  important  part  is  very  great,  and  the  products  differ  from  each 
other  materially  in  their  composition  and  in  their  physiological  action. 
They  may  be  divided  into  four  classes,  the  classification  being  based  upon 
the  sources  from  which  they  are  obtained  and  upon  the  method  of  their 
preparation. 

I. — Those  prepared  by  the  fermentation  of  malted  grain — beers,  ales, 
and  porters. 

II. — Those  prepared  by  the  fermentation  of  grape- juice — wines. 

III. — Those  prepared  by  the  fermentation  of  the  juices  of  fruits  other 
than  the  grape — eider,  fwdt-wines. 

IV. — Those  prepared  by  the  distillation  of  some  fermented  saccharine 
liquid — ardent  spirits. 


ALCOHOLIC    BEVERAGES.  175 

J3eer,  ale,  and  porter  are  aqueous  infusions  or  decoctions  of  malted 
grain  (occasionally  of  rice,  maize,  or  potatoes),  fermented  and  flavored 
with  hops;  they  contain,  therefor,  the  soluble  constituents  of  the  grain 
employed;  dextrine  and  glucose,  produced  during  the  malting;  alcohol 
and  carbon  dioxide  produced  during  the  fermentation;  and  the  soluble 
constituents  of  the  flavoring  material.  Their  color,  which  varies  from  pale 
amber  to  dark  brown,  depends  upon  the  proportion  of  malt,  dried  at  a  high 
temperature,  used  in  their  preparation. 

The  alcoholic  strength  of  malt  liquors  varies  from  1.5  to  9  per  cent. 
Weiss  bier  contains  1.5 — 1.9  percent.;  lager,  4.1 — 4.5  per  cent.;  bock  bier, 
3.88 — 5.23  per  cent.;  London  porter,  5.4 — G.9  per  cent.;  Burton  ale,  5.9  per 
cent. ;  Scotch  ale,  8.5 — 9  per  cent.  Malt  liquors  all  contain  a  considerable 
quantity  of  nitrogenous  material  (0.4 — 1  percent.  N.),  andsuccinic,  lactic, 
and  acetic  acids.  The  amount  of  inorganic  material,  in  which  the  phos- 
phates of  potassium,  sodium,  and  magnesium  predominate  largely,  varies 
from  0.2  to  0.3  per  cent.  The  amount  of  water  varies  from  79.66  in  Bur- 
ton ale,  to  91.8  in  weiss  bier.  The  specific  gravity  from  1.014  to  1.033. 

The  adulterations  of  malt  liquors  are  numerous  and  varied.  Water 
is  added  to  increase  bulk;  it  may  be  detected  by  the  taste,  and  by  the 
low  specific  gravity  of  the  beer  deprived  of  its  alcohol.  Sodium  carbonate 
is  frequently  added  with  the  double  purpose  of  neutralizing  an  excess  of 
acetic  acid  and  increasing  the  foam.  The  most  serious  adulteration  of 
beer  consists,  however,  in  the  introduction  of  bitter  principles  other  than 
hops,  and  notably  of  strychnine,  cocculus  indicus  (picrotoxin),  and  picric 
acid.  Of  late  years  artificial  glucose  (made  from  starch  by  the  action  of 
dilute  sulphuric  acid)  has  been  used  by  some  brewers;  a  substitution 
which  would  be  perfectly  justifiable  and  harmless,  were  it  not  for  the  fact 
that  glucose  prepared  in  this  way  is  frequently,  if  not  always,  contami- 
nated with  arsenic,  which  it  derives  from  the  acid  used  in  its  manufacture. 

Wines  have  been  in  use  from  remote  antiquity,  and  are  prepared  in 
infinite  variety  in  almost  all  temperate  countries. 

The  grapes  are  collected  with  more  or  less  care,  and  in  different 
degrees  of  ripeness;  for  the  finest  grades  each  berry  is  separately  plucked 
as  it  reaches  the  proper  degree  of  ripeness;  for  the  commonest  ripe,  un- 
ripe, and  damaged  grapes  are  thrown  into  the  press  indiscriminately.  In 
the  manufacture  of  most  red  wines  and  of  champagnes,  the  grape  is  not 
allowed  to  reach  full  maturity.  The  grapes  are  expressed,  and  the  juice, 
together  with  the  skins  and  seeds,  or  marc,  is  placed  in  a  butt  with  a 
perforated  bottom,  through  which  it  is  allowed  to  trickle  into  the  fer- 
mentation vats;  in  the  case  of  red  wines  the  marc  is  allowed  to  remain  in 
contact  with  the  must,  or  juice,  during  a  part  at  least  of  the  fermentation, 
in  order  that  the  alcohol  developed  may  take  up  a  proper  quantity  of 
coloring  matter;  in  the  case  of  white  wines,  contact  with  a  small  quantity 
of  the  stalks  is  necessary  to  avoid  stringiness.  The  fermentation  of  the 
must,  which  takes  place  without  the  addition  of  yeast,  requires  about 
fourteen  days,  at  the  end  of  which  the  wine  is  drawn  off  from  the  lees 
into  barrels,  in  which  it  is  kept  at  a  low  temperature,  and  protected  from 
the  air  as  far  as  possible,  to  avoid  the  establisment  of  acetic  fermentation. 
If  the  must  be  rich  in  glucose  and  poor  in  nitrogenized  material,  and  if 
the  fermentation  be  arrested  before  the  glucose  has  been  entirely  con- 
verted into  alcohol,  a  sweet  wine  is  obtained;  under  the  contrary  con- 
ditions a  dry  wine  is  the  result.  During  the  fermentation,  as  the  per- 
centage of  alcohol  increases,  acid  potassium  tartrate  is  deposited,  being 
insoluble  in  alcoholic  liquids.  Tartaric  acid  is  the  predominating  acid  in 


176  GENERAL    MEDICAL    CHEMISTKY. 

the  grape;  while  in  other  fruits  malic  and  citric  acids,  whose  acid  salts 
are  soluble  in  alcoholic  liquids,  exist  in  greater  proportions;  hence,  the 
fermented  drinks  prepared  from  fruit  other  than  grapes  are  sharp  and 
thin  in  taste. 

Most  wines  of  good  quality  improve  in  flavor  with  age,  and  this  im- 
provement is  greatly  hastened  by  t^e  process  of  pasteuriny,  which  con- 
sists simply  in  warming  the  wine  to  a  temperature  of  60°  C.,  without 
contact  of  air. 

Wines  grown  in  different  districts,  and  from  different  kinds  of  grapes, 
differ  greatly  in  their  appearance,  flavor,  color,  and  alcoholic  strength; 
they  may  be  divided  into  two  classes — light  and  heavy  wines. 

Light  wines  are  those  whose  percentage  of  alcohol  is  less  than 
twelve  per  cent.  In  this  class  are  included  the  red  and  white  French  and 
German  wines,  clarets,  Sauternes,  Rhine,  and  Moselle  wines;  champagnes, 
Burgundies,  the  American  wines,  except  some  varieties  of  California 
wine,  Australian,  Greek,  Hungarian,  and  Italian  wines. 

The  champagnes  and  some  Moselle  whines  are  sparkling,  a  quality 
which  is  communicated  to  them  by  bottling  them  before  the  fermentation 
is  completed,  thus  retaining  the  carbon  dioxide,  which  is  dissolved  by 
virtue  of  the  pressure  which  it  exerts.  They  are  dry  and  sweet  in  pro- 
portion as  the  sugar  is  completely  or  partially  consumed  during  the  fer- 
mentation. When  properly  prepared  they  are  agreeable  to  the  palate, 
and  assist  the  digestion;  when  new,  however,  they  are  liable  to  com- 
municate their  fermentation  to  the  contents  of  the  stomach  and  thus  seri- 
ously disturb  digestion. 

Of  the  still  wines,  the  most  widely  used  are  the  clarets,  or  red  Bor- 
deaux wines,  and  the  hocks,  or  white  Rhine  and  Moselle  wines.  The 
former  are  of  low  alcoholic  strength,  mildly  astringent,  and  contain  but  a 
small  quantity  of  nitrogenous  material,  qualities  which  render  them  par- 
ticularly adapted  to  table  use  and  as  mild  stimulants,  especially  for  those 
predisposed  to  gout.  The  Rhine  wines  are  thinner  and  more  acid,  and 
generally  of  lower  alcoholic  strength  than  the  clarets.  The  Burgundy 
and  Rhone  wines  are  celebrated  for  their  high  flavor  and  body;  they  are 
not  strongly  alcoholic,  but  contain  a  large  quantity  of  nitrogenous  ma- 
terial, to  which  they  are  indebted  for  their  notoriety  as  developers  of 
gout. 

Our  native  American  wines,  particularly  those  of  the  Ohio  valley  and 
of  California,  are  yearly  improving  in  flavor  and  quality;  they  more  closely 
resemble  the  Rhine  wines  and  Sauternes  than  other  European  wines. 

Heavy  wines  are  those  whose  alcoholic  strength  is  greater  than  twelve 
per  cent,  usually  fourteen  to  seventeen  per  cent;  they  include  the  sherries, 
ports,  Madeiras,  Marsala,  and  some  California  wines,  arid  are  all  the  pro- 
ducts of  warm  climates. 

Sherry  is  an  amber-colored  wine,  grown  in  the  south  of  Spain,  and 
officinal  under  the  name  of  Vinum  Xericum  (U.  S.,  Br.).  Marsala  closely 
resembles  sherry  in  appearance,  and  is  frequently  substituted  for  it. 
Port,  officinal  as  Vinum  portense  (U.  S.),  is  a  rich,  dark  red  wine,  grown 
in  Portugal. 

The  adulteration  of  wine  by  the  addition  of  foreign  substances 
is  confined  almost  entirely  to  their  artificial  coloration,  which  is  pro- 
duced by  the  most  various  substances,  indigo,  logwood,  fuchsine,  etc, 
(see  Bull.  d.  1.  Soc.  Chim.  xxv.,  435,  483,  530).  The  addition  of  natural 
constituents  of  wines,  obtained  from  other  sources,  and  the  mixing  of 
different  grades  of  wine  are,  however,  extensively  practised.  Water  and 


ALCOHOLIC    BEVERAGES. 


177 


alcohol  are  the  chief  substances  so  added;  an  excess  of  the  former  may  be 
detected  by  the  taste,  and  the  low  specific  gravity  after  expulsion  of  the 
alcohol.  Most  wines  intended  for  export  are  fortified  by  the  addition  of 
alcohol;  when  the  alcoholic  spirit  used  is  free  from  arnyl  alcohol,  and  is 
added  in  moderate  quantities,  there  can  be  no  serious  objection  to  the 
practice,  especially  when  applied  to  certain  wines  which,  without  such 
treatment,  do  not  bear  transportation.  The  mixing  of  fine  grades  of  wine 
with  those  of  a  poorer  quality  is  extensively  practised,  particularly  with 
champagnes,  clarets,  and  burgundies,  and  is  perfectly  legitimate.  The 
same  cannot  be  said,  however,  of  the  manufacture  of  factitious  wine, 
either  entirely  from  materials  not  produced  from  the  grape,  or  by  con- 
verting white  into  red  wines,  or  by  mixing  wines  with  coloring  matters, 
alcohol,  etc.,  to  produce  imitations  of  wines  of  a  different  class,  an  indus- 
try which  flourishes  extensively  in  Normandy,  at  Bingen  on  the  Rhine, 
and  at  Hamburg.  The  wines  so  produced  are  usually  heavy  wines,  port 
and  sherry,  so-called. 

In  the  following  table  are  given,  in  percentages  by  weight,  the  chief 
constituents  of  the  more  generally  used  varieties  of  wine: 


Specific  gravity. 

Alcohol  by  weight. 

f 

I 
11 

K 

Volatile  acid, 
acetic. 

Total  acid  as  tar- 
taric. 

Grape  sugar. 

1 

1 

B. 

"H 

Claret           

999.8 

10.44 

.374 

.137 

.580 

2.255 

1.64 

.223 

.18 

Sauterne      

992.2 

10.84 

.435 

.169 

.634 

.088 

1.82 

.197 

18 

992.2 

10.73 

.435 

.169 

.634 

.088 

1  82 

.197 

.18 

Chablis  

992.2 

7.77 

.435 

.169 

.634 

.088 

1.46 

.197 

.1$ 

Rhine  wine                  ... 

993.5 

9.98 

.440 

.217 

.538 

.310 

1.25 

182 

1& 

992.5 

10.81 

.386 

.191 

.628 

.310 

1.25 

.122 

18- 

Hungarian,  white 

991.6 

10.23 

.419 

.179 

.644 

.310 

1-25 

.047 

18 

Sherry  

992.9 

17.89 

.390 

.055 

.458 

2.043 

.437 

.18; 

938.0 

16.98 

.379 

.045 

.435 

.934 

.567 

.IB 

Sherry   imitation 

996.0 

16.48 

257 

.111 

.397 

2.23 

327 

18 

Madeira 

1001.3 

16  12 

.528 

-071 

.610 

3.0 

402 

345 

.18 

Marsala  

999.5 

16  38 

241 

.117 

.389 

.275 

3.94 

.311 

026 

Port  

992.2 

1208 

.556 

.048 

.616 

.669 

4.49 

.247 

026 

Malaga  

1057.0 

12.04 

.556 

.048 

.616 

14.62 

18.5 

.38 

.026 

Tokay     . 

1038.0 

12.04 

.556 

048 

.616 

1462 

1  06 

38 

026 

Norton's  Virginia     .... 

1038.0 

953 

556 

.048 

.616 

14.62 

2  74 

.38 

.026 

Catawba  

1038.0 

9  61 

.556 

.048 

.616 

14.62 

1.7 

.38 

026 

Cider  is  the  fermented  juice  of  the  apple,  prepared  very  much  in  the 
same  way  as  wine  is  from  grape-juice  and  containing  3.5  to  7.5  per  cent,  of 
alcohol.  It  is  very  prone  to  acetous  fermentation,  which  renders  it  sour 
and  not  only  unpalatable,  but  liable  to  produce  colic  and  diarrhoea  with 
those  not  hardened  to  its  use. 

Spirits  are  alcoholic  beverages,  prepared  by  fermentation  and  distilla- 
tion. They  differ  from  beers  and  wines  in  containing  a  greater  propor- 
tion of  alcohol,  and  in  not  containing  any  of  the  non-volatile  constituents 
of  the  grains  or  fruits  from  which  they  are  prepared.  Besides  alcohol 
and  water  they  contain  acetic,  butyric,  valerianic  and  cenanthic  ethers, 
to  which  they  owe  their  flavor;  sometimes  tannin  and  coloring  matter 
derived  from  the  cask;  amylic  alcohol  remaining  after  imperfect  purifica- 
12 


178  GENERAL    MEDICAL    CHEMISTRY. 

tion;  sugar  intentionally  added;  and  caramel.  It  is  to  the  last-named  sub- 
stance that  all  dark  spirits  owe  their  color;  although,  after  long  keeping 
in  wood  a  naturally  colorless  spirit  assumes  a  straw  color. 

The  varieties  of  spirituous  beverages  in  common  use  are: 

Brandy,  spiritus  vini  .gallici  (U.  S.,  Br.),  obtained  by  the  distillation 
of  wine,  and  manufactured  in  France  and  in  California  and  Ohio.  It  is 
of  sp.  gr.  0.929  to  0.934,  is  dark  or  light  in  color,  according  to  the  quantity 
of  burnt  sugar  added,  and  contains  about  1.2  per  cent,  of  solid  matter,  of 
which  0.05  to  0.2  per  cent,  is  ash.  An  inferior  grade  of  brandy  is  pre- 
pared in  wine-growing  countries  from  the  marc,  or  mass  of  grape-pulp, 
etc.,  left  in  the  wine-press. 

American  whiskey,  spiritus  frumenti  (U.  S.),  prepared  from  wheat, 
rye,  barley,  or  Indian  corn;  has  a  specific  gravity  of  0.922  to  0.937  and 
contains  0.1  to  0.3  per  cent,  of  solids.  Its  color  is  due  partly  to  coloring 
matter  from  the  wood  of  the  cask,  but  mainly  to  added  caramel. 

Scotch  and  Irish  whiskies,  colorless  spirits  distilled  from  fermented 
grains;  sp.  gr.  0.915  to  0.920,  having  a  peculiar  smoky  flavor  produced  by 
drying  the  malted  grain  by  a  peat  fire. 

Gin,  also  distilled  from  malted  grain,  sp.  gr.  0.930  to  0.944,  flavored 
with  juniper  and  sometimes  fraudulently  with  turpentine. 

Hum. — A  spirit  distilled  from  molasses,  and  varying  in  color  and 
flavor  from  the  dark  Jamaica  rum  to  the  colorless  St.  Croix  rum.  The 
former  is  of  sp.  gr.  0.914  to  0.926,  and  contains  one  per  cent,  of  solid 
matter,  of  which  0.1  per  cent,  of  ash. 

Liqueurs  are  spirits  sweetened  and  flavored  with  vegetable  aromatics, 
and  frequently  colored;  anisette  is  flavored  with  aniseed;  absinthe,  with 
wormwood;  curagoa,  with  orange-peel;  kirschwasser,  with  cherries,  the 
stones  being  cracked  and  the  spirits  distilled  from  the  bruised  fermented 
fruit;  kiimmel, with  cummin  and  caraway  seeds;  maraschinotv?ith  cherries; 
noyeau,  with  peach  and  apricot  kernels. 

Propyl  Hydrate. 

Primary  propyl  alcohol — Ethyl  carbinol — C3H7OH — is  produced, 
along  with  ethylic  alcohol,  during  fermentation,  and  obtained  by  fractional 
distillation  of  marc  brandy,  from  cognac  oil,  huilede  marc  (not  to  be  con- 
founded with  oil  of  wine),  an  oily  matter,  possessing  to  a  high  degree 
the  flavor  of  brandy,  which  separates  from  marc  brandy,  distilled  at  high 
temperatures;  and  from  the  residues  of  manufacture  of  alcohol  from  beet- 
root, grain,  molasses,  etc.  It  is  a  colorless  liquid,  has  a  hot  alcoholic 
taste,  and  a  fruity  odor;  it  boils  at  96.7°;  and  is  miscible  with  water.  It 
has  not  been  put  to  any  use  in  the  arts.  Its  intoxicating  and  poisonous 
actions  are  greater  than  those  of  ethyl  alcohol.  It  exists  in  small 
quantity  in  cider. 

There  exists  a  secondary  propyl  alcohol,  or  isopropyl  alcohol  or  di- 
methyl carbinol — CH  (CHS)2HO — which  is  formed  by  the  action  of 
nascent  hydrogen  upon  acetone;  it  boils  at  86°. 

Butyl  Alcohols— C4H9OH. 

Theoretically  there  are  four  possible  butyl  alcohols;  two  primary,  one 
secondary,  and  one  tertiary  ;  of  these  three  have  been  obtained  : 

Primary,  normal  butyl  alcohol — Butyl  alcohol  of  fermentation — Pro- 


AMYLIC    ALCOHOLS.  179 

pyl  carUnol — CH3 — CH2 — CH2 — CH2OH— is  formed  in  small  quantities 
during  alcoholic  fermentation,  and  may  be  obtained  by  repeated  fractional 
distillation  from  the  oily  liquid  left  in  the  rectification  of  vinic  alcohol.  It 
is  a  colorless  liquid;  boils  at  114.7°;  soluble  in  10  parts  water,  from  which 
it  separates  on  the  addition  of  a  salt  soluble  in  water.  It  is  more  actively 
poisonous  than  ethyl  or  methyl  alcohol. 

Secondary  butyl  alcohol;  ethyl-methyl  carbinol — CH3 — 


a  liquid  which  boils  at  99°. 

Tertiary  butyl  alcohol;  trimethyl  carbinol,  CH3 — COH — a  crystalline 
solid,  which  fuses  at  20°— 25°,  and  boils  at  82°. 

Amylic  Alcohols— C6Hn  OH. 

Of  the  eight  amylic  alcohols  whose  existence  theoretical  considerations 
point  out  as  possible  (see  p.  152),  seven  have  been  separated.  The  sub- 
stance usually  known  as  amylic  alcohol,  potato  spirit,  fusel  oil,  alcohol 
amylicum  (U.S.,  Br.),  is  a  mixture  in  varying  proportions  of  the  two 

primary  alcohols;  ™3\CH— CH2— CH2OH  and  CH*~^^>CH— CH, 

OH;  the  former  differing  from  the  latter  in  that  it  deviates  the  plane  of 
polarization  to  the  left  ([a]  =  —4°  3G");  in  its  boiling-point  being  2° 
lower,  and  in  the  greater  solubility  of  the  amyl-sulphate  of  barium  ob- 
tained from  it. 

It  is  formed  during  alcoholic  fermentation  of  glucose  in  greater 
abundance  than  any  of  the  alcohols  other  than  the  ethylic;  owing  to  its 
high  boiling-point,  it  is  in  great  part  retained  in  the  oily  material  which 
collects  in  the  still  during  the  rectification  of  alcohol  and  spirits;  a  por- 
tion, however,  passes  over  and  is  removed  by  subsequent  treatment  (see 
below). 

It  is  obtained  from  the  last  milky  products  of  rectification  of  alcoholic 
fluids  made  from  grain  or  potatoes;  these  are  shaken  with  water  to  re- 
move ethyl  alcohol,  the  supernatant  oily  fluid  is  decanted,  dried  by  con- 
tact with  fused  calcium  chloride,  and  distilled;  that  portion  which  passes 
over  between  128°  and  132°  being  collected. 

It  is  a  colorless,  oily  liquid,  has  an  acrid  taste  and  a  peculiar  odor,  at 
first  not  unpleasant,  afterward  nauseating  and  provocative  of  severe 
headache;  it  boils  at  132°  and  crystallizes  at  —20°;  sp.gr.  0.8184  at  15°; 
it  mixes  with  alcohol  and  ether,  but  not  with  water.  It  burns  difficultly 
with  a  pale  blue  flame. 

When  exposed  to  air  it  oxidizes  very  slowly;  quite  rapidly,  however, 
in  contact  with  platinum-black,  forming  valerianic  acid.  The  same  acid, 
along  with  other  substances,  is  produced,  by  the  action  of  the  more 
powerful  oxidants  upon  amyl  alcohol. 

Chlorine  attacks  it  energetically,  forming  amyl  chloride,  hydrochloric 
acid,  and  other  chlorinated  derivatives.  Sulphuric  acid  dissolves  in  amyl 
alcohol,  with  formation  of  amyl-sulphuric  acid,  SO4  (CBHn)H,  correspond- 
ing to  ethyl-sulphuric  acid.  It  also  forms  similar  acids  with  phosphoric, 
oxalic,  citric,  and  tartaric  acids. 


180  GENERAL   MEDICAL    CHEMISTRY. 

Although  not  fragrant  itself,  its  ethers,  when  dissolved  in  ethyl  alco- 
hol, have  the  taste  and  odor  of  various  fruits,  and  are  used  in  the  prepa- 
ration of  artificial  fruit-essences.  Amyl  alcohol  is  also  used  in  analysis 
as  a  solvent,  particularly  for  certain  alkaloids,  and  in  pharmacy  for  the 
artificial  production  of  vaUrianic  acid  and  the  valerianates. 

Its  vapor,  when  inhaled,  produce's  severe  headache,  a  sense  of  suffo- 
cation, giddiness,  and,  in  large  doses,  death.  The  liquid,  taken  internally, 
especially  when  in  alcoholic  solution,  is  much  more  actively  poisonous 
than  ethylic  alcohol.  Even  in  very  dilute  solution  it  produces  the  rapid 
intoxication,  and  severe  headache  and  vertigo,  which  are  prominent  ef- 
fects of  inferior  whiskey. 

To  free  spirits  of  amyl  alcohol,  to  defuselate  them,  advantage  is  usu- 
ally taken  of  the  absorbent  power  of  freshly  burnt  wood  charcoal,  which 
is  either  placed  in  the  still  or  made  into  a  filter,  through  which  the  spirit 
is  passed  after  distillation,  or,  preferably,  the  vapor  from  the  still  is  made 
to  pass  through  a  layer  of  charcoal  before  condensation. 

Spirits  properly  freed  of  fusel  oil  give  off  no  irritating  or  foul  fumes 
when  hot;  they  are  not  colored  red  when  mixed  with  three  parts  ethyl 
alcohol  and  one  part  strong  sulphuric  acid;  they  are  not  colored  red  or 
black  by  ammoniacal  silver  nitrate  solution;  when  one  hundred  and  fifty 
parts  of  the  spirit  mixed  with  one  part  potash,  dissolved  in  a  little  water, 
are  evaporated  down  to  fifteen  parts,  and  mixed  with  an  equal  volume  of 
dilute  sulphuric  acid,  no  offensive  odor  should  be  given  off. 

No  practical  interest  attaches  to  the  alcohols  of  this  series  interme- 
diate between  amyl  alcohol  and 


Cetyl  Hydrate. 

Cetylic  alcohol — Ethal — C16H33OH — is  obtained  by  the  saponification 
of  spermaceti  (its  palmitic  ether)  by  potash.  It  is  a  white,  crystalline 
solid,  fusible  at  49°,  and  capable  of  distillation  at  a  high  temperature; 
insoluble  in  water;  soluble  in  alcohol  and  ether;  tasteless  and  odorless. 

Ceryl  hydrate — C27H55OH — cerylic  or  cerotic  alcohol,  and  Myricyl 
hydrate — C30H61OH — myricic  or  mellissic  alcohol — are  obtained  as  white, 
crystalline  solids:  the  former  from  China  wax;  the  second  from  beeswax, 
by  saponification  by  potash. 


SIMPLE  ETHERS. 

OXIDES  OF  ALCOHOLIC  RADICALS  OF  THE  SERIES 

Methyl  Oxide. 


I  C*H  ) 

Methylic  6^r,C2H6O—  ^jj3  >•  O  —  isomeric  with  ethylic  alcohol,  is  ob- 

tained by  the  action  of  sulphuric  and  boric  acids  upon  methyl  alcohol,  or 
by  the  action  of  silver  oxide  upon  methyl  iodide. 

It  is  a  colorless  gas,  has  an  ethereal  odor,  burns  with  a  pale  flame, 
liquefies  at  —36°,  and  distils  at  —21°;  is  soluble  in  water,  ethyl  alcohol, 
and  sulphuric  acid,  less  abundantly  in  methyl  alcohol. 


ETHYL    OXIDE.  181 


Ethyl  Oxide. 

Ethylic  ether — Ether — Sulphuric  ether — Either fort  lor  (U.  S.) — JEther 

O  TT   ) 

purus  (Br.) — C4H10O  —  (i2rr6  r  O — was    discovered    in  the  sixteenth  cen- 
tury by  Val.  Cordus,  who  called  it  oleum  vini  dulce. 

It  is  obtained  by  the  action  of  sulphuric  acid  upon  alcohol,  whence  the 
name  of  "  sulphuric  ether  "  is  improperly  given  it.  A  mixture  is  made 
of  five  parts  alcohol,  ninety  per  cent.,  and  nine  parts  of  concentrated 
sulphuric  acid,  in  a  vessel  surrounded  by  cold  water.  This  mixture  is 
introduced  into  a  retort,  over  which  is  conveniently  arranged  a  vessel 
from  which  a  slow  stream  of  alcohol  can  be  made  to  enter  the  retort.  Heat 
is  applied  by  a  sand-bath,  and  the  addition  of  alcohol  is  so  regulated  that 
the  temperature  does  not  rise  above  140°.  The  retort  is  connected  with 
a  well-cooled  condenser,  and  the  process  continued  until  the  temperature 
in  the  retort  rises  above  the  point  indicated.  It  is  important  that  the  tube 
by  which  the  alcohol  is  introduced  be  drawn  out  to  a  small  opening,  and 
dip  well  down  below  the  surface  of  the  liquid.  The  distillate  thus  ob- 
tained contains,  besides  ether,  alcohol,  water,  and  gases  resulting  from  the 
decomposition  of  the  alcohol  and  sulphuric  acid,  notably  sulphur  dioxide. 
It  is  subjected  to  a  first  purification  by  shaking  with  water  containing 
potash  or  lime,  decanting  the  supernatant  ether,  and  redistilling.  The 
product  of  this  process  is  "washed  ether"  or  "aether,  U.  S."  It  is  still 
contaminated  with  water  and  alcohol,  and  when  desired  pure,  as  for  pro- 
ducing anaesthesia  and  for  processes  of  analysis,  it  is  subjected  to  a  second 
purification.  It  is  again  shaken  with  water,  decanted  after  separation, 
shaken  with  recently  fused  calcium  chloride  and  newly  burnt  lime,  vvitli 
which  it  is  left  in  contact  twenty-four  hours,  and  from  which  it  is  then 
distilled. 

It  was  known  at  an  early  day  that  a  small  quantity  of  sulphuric  acid 
is  capable  of  converting  a  large  quantity  of  alcohol  into  ether,  and  that 
at  the  end  of  the  process  the  sulphuric  acid  remains  in  the  retort  unal- 
tered, except  by  secondary  reactions.  A  metaphysical  explanation  of  the 
process  was  found  in  the  assertion  that  the  acid  acted  by  its  mere  presence, 
by  catalysis,  as  it  was  said;  in  other  words,  it  acted  because  it  acted,  a 
very  ready  but  a  very  feminine  method  of  explaining  what  is  not  under- 
stood, which,  we  are  sorry  to  say,  is  still  invoked  by  some  authors  as  a 
covering  for  our  ignorance  of  the  rationale  of  certain  chemico-physiologi- 
cal  phenomena. 

It  was  only  in  1850  that  Alex.  Williamson,  by  a  series  of  ingenious 
and  carefully  conducted  experiments,  determined  the  true  nature  of  the 
process.  In  the  conversion  of  alcohol  into  ether,  an  intermediate  sub- 
stance, sulphovinio  acid,  plays  an  important  part,  being  alternately  formed 
at  the  expense  of  the  alcohol,  and  destroyed  with  formation  of  ether  and 
regeneration  of  sulphuric  acid.  At  first  sulphuric  acid  and  alcohol  act 
upon  each  other,  molecule  for  molecule,  to  form  water  and  sulphovinic 
acid : 


182  GENERAL    MEDICAL    CHEMISTRY. 

The  new  acid,  as   soon  as  formed,  reacts  with  a  second  molecule  of 
alcohol,  with  regeneration  of  sulphuric  acid  and  formation  of  ether: 


Theoretically,  therefor,  a  given  quantity  of  sulphuric  acid  could  con- 
vert an  unlimited  amount  of  alcohol  into  ether;  such  would  also  be  the 
case  in  practice,  were  it  not  that  the  acid  gradually  becomes  too  dilute,  by 
admixture  with  the  water  formed  during  the  reaction,  and  at  the  same 
time  is  decomposed  by  secondary  reactions,  into  which  it  enters  with  im- 
purities in  the  alcohol;  causes  which  in  practice  limit  the  amount  of  ether 
produced  to  about  four  to  five  times  the  bulk  of  acid  used. 

Properties. — Ether  is  a  colorless,  limpid,  mobile,  highly  refracting 
liquid;  it  has  a  sharp,  burning  taste,  and  a  peculiar,  tenacious  odor,  char- 
acterized as  ethereal.  Sp.  gr.  0.723  at  12.5°,  and  0.7364  at  0°;  it  boils  at 
34.5°,  and  crystallizes  at  — 31°.  Its  tension  of  vapor  is  very  great,  especially 
at  high  temperatures;  it  should,  therefor,  be  stored  in  strong  bottles,  and 
should  be  kept  in  situations  protected  from  elevations  of  temperature.  It 
is  exceedingly  volatile,  and,  when  allowed  to  evaporate  freely,  absorbs  a 
great  amount  of  heat,  of  which  property  advantage  is  taken  to  produce 
local  anaesthesia,  the  part  being  benumbed  by  the  cold  produced  by  the 
rapid  evaporation  of  ether  sprayed  upon  the  surface.  Water  dissolves  one- 
ninetieth  its  weight  of  ether,  and  ether  dissolves  one  thirty-sixth  its  weight 
of  water.  Ethylic  and  methylic  alcohols  are  miscible  with  it  in  all  pro- 
portions. Ether  is  an  excellent  solvent  of  many  substances  not  soluble  in 
water  and  alcohol,  while,  on  the  other  hand,  it  does  not  dissolve  many  sub- 
stances soluble  in  those  fluids,  properties  which  are  of  great  value  in  prox- 
imate organic  analysis.  The  resins  and  fats  are  readily  soluble  in  ether; 
the  salts  of  the  alkaloids  and  many  vegetable  coloring  matters  are  soluble 
in  alcohol  and  water,  but  insoluble  in  ether,  while  the  free  alkaloids  are 
for  the  most  part  soluble  in  ether,  but  insoluble,  or  very  sparingly  soluble, 
in  water. 

Ether,  whether  in  the  form  of  vapor  or  of  liquid,  is  highly  inflammable; 
the  liquid  burns  with  a  luminous  flame.  The  vapor  forms  with  air  a  vio- 
lently explosive  mixture;  it  is  denser  than  air,  through  which  it  falls  and 
diffuses  itself  to  a  great  distance;  and  great  caution  is  therefor  required 
in  handling  ether  in  a  locality  in  which  there  is  a  light  and  fire,  especially 
if  the  fire  be  near  the  floor. 

Pure  ether  is  neutral  in  reaction,  but,  on  exposure  to  air  or  oxygen, 
especially  in  the  light,  it  becomes  acid  from  the  formation  of  a  small  quan- 
tity of  acetic  acid. 

Sulphuric  acid  mixes  with  ether  with  elevation  of  temperature  and  for- 
mation of  sulphovinic  acid;  sulphuric  anhydride  forms  ethyl  sulphate. 
Nitric  acid,  aided  by  heat,  oxidizes  ether  to  carbon  dioxide  and  acetic  and 
oxalic  acids.  Ether,  saturated  with  hydrochloric  acid  and  distilled,  yields 
ethyl  chloride. 

Chlorine,  in  the  presence  of  water,  oxidizes  ether,  with  formation  of 
aldehyde,  acetic  acid,  and  chloral.  In  the  absence  of  water,  however,  a 
series  of  products  of  substitution  are  produced,  in  which  two,  four,  and 
ten  atoms  of  hydrogen  are  replaced  by  a  corresponding  number  of  atoms 
of  chlorine.  These  substances  in  turn,  by  substitution  of  alcoholic  rad- 
icals, or  of  atoms  of  elements,  for  atoms  of  chlorine,  give  rise  to  other  de- 
rivatives. 


MONOBASIC    ACIDS.  183 

Ether  is  largely  used  in  the  chemical  arts,  in  pharmacy,  and  in  the 
laboratory  as  a  solvent,  in  the  preparation  of  compound  ethers,  and  for  the 
production  of  cold.  Its  chief  use  in  medicine  is  as  an  anaesthetic,  being  the 
safest  and  most  readily  handled  that  we  possess.  When  taken  in  overdose 
it  causes  death,  although  it  is  by  no  means  as  liable  to  give  rise  to  fatal 
accidents  as  is  chloroform,  and,  as  it  seems  to  be  without  direct  action  upon 
/  the  nerve-centres.  Patients  suffering  from  an  overdose  may,  in  the  vast 
majority  of  cases,  be  resuscitated  by  artificial  respiration  and  the  induced 
current,  one  pole  to  be  applied  to  the  nape  of  the  neck,  and  the  other 
carried  across  the  body  just  below  the  anterior  attachments  of  the  dia- 
phragm. 

In  cases  of  death  from  ether  the  odor  is  generally  well  marked  in  the 
clothing  and  surroundings,  and  especially  on  opening  the  thoracic  cavity. 
In  the  analysis  it  is  sought  for  in  the  blood  and  lungs  at  the  same  time 
as  chloroform  (q.  v.). 

The  oxides  of  the  remaining  alcoholic  radicals  may  be  obtained  by 
processes  similar  to  those  used  in  the  preparation  of  ethylic  ether. 

Mixed  ethers  differ  from  the  simple  ethers  (which  may  be  regarded 
as  water  in  which  both  atoms  of  hydrogen  are  replaced  by  like  alcoholic 

O  TT    ) 
radicals,    /V-rr5  [  O  —  ethylic  ether)  in  that  the  two  atoms  of  hydrogen 

OTT   ) 
are  replaced  by  unlike  alcoholic  radicals,   ^  -^  I  O,  methyl-ethyl  oxide. 

They  may  be  readily  obtained  by  the  action  of  the  iodide  of  one  alco- 
holic radical  upon  the  potassium  or  sodium  oxide  of  the  other: 


Methyl  iodide.         Ethyl  sodium     Sodium  iodide.      Ethyl  methyl 
oxide.  oxide. 

As  with  each  alcoholic  iodide  there  can  be  formed  as  many  mixed 
ethers  as  there  are  other  monoatomic  alcohols,  it  may  be  readily  under- 
stood that  substances  of  this  class  are  very  numerous. 

None  of  them  have  hitherto  been  applied  to  industrial  or  medicinal 
uses. 


MONOBASIC  ACIDS. 

SERIES  CnHanOa. 

The  members  of  this  series,  although  formed  in  a  variety  of  ways, 
may  be  considered  as  derived  from  the  alcohols  of  the  series  CnH2n+2O, 
by  the  substitution  of  an  atom  of  oxygen  for  two  atoms  of  hydrogen,  by 
oxidation  of  the  radical. 

As  the  higher  terms  exist  in  the  fats,  and  as  the  lower  members  of 
the  series  are  volatile,  they  are  frequently  designated  as  the  volatile  fatty 
acids.  They  form  an  homologous  series,  the  known  terms  of  which  are 
given  in  the  table  on  following  page. 

They  all  exist  in  nature,  either  free  or  in  combination  as  salts  or 
ethers,  some  of  which  are  important  articles  of  food,  and  others  sub- 
stances valuable  as  medicinal  agents. 


184 


GENERAL   MEDICAL    CHEMISTRY. 


Name. 

Formula. 

Fusing- 
point. 

Boiling- 
point. 

Formic  acid  r  .  .  . 

CUO2H 

1° 

100° 

.Acetic  acid  

C  H  O  II 

17° 

119 

Propionic  acid  

C3H  (XH 

140 

Butyric  acid  

C4HOH 

—20° 

160 

Valerianic  acid.  .    ,  

CH  OH 

175 

Caproic  acid  

CeH   OH 

1  90 

198 

CH  OH 

212 

CH  OH 

14° 

236 

Pelaro"onic  acid  

CH  OH 

18° 

260 

Capric  acid  

C  H  d  H 

27° 

Laurie  acid  

C  H  OH 

43.5° 

Myristic  acid  

C  H   OH 

53.8° 

C  H  OH 

62° 

Margaric  acid  

C  ,H,,O  H 

60° 

Stearic  acid  

C  H  OH 

69° 

Arachic  acid  

C  H  OH 

75° 

C  H  OH 

76° 

Hysenic  acid  

C  H  OH 

77° 

Cerotic  acid        

C  H  OH 

78° 

C  H  OH 

88° 

Formic  Acid— CHaOa-CH^ 

Is  widely  distributed  in  the  animal  and  vegetable  kingdoms.  As  its 
name  implies,  it  exists  in  the  acid  secretion  of  red  ants,  from  whose  bod- 
ies it  was  first  obtained;  it  occurs  also  in  the  stinging  hairs  of  certain  in- 
sects, in  the  blood,  urine,  bile,  perspiration,  and  muscular  fluid  of  man,  in 
the  stinging-nettle,  in  the  leaves  of  trees  of  the  pine  family,  and, 
finally,  in  certain  mineral  waters. 

Formic  acid  is  also  produced  in  a  number  of  reactions.  By  the  oxida- 
tion of  many  organic  substances,  sugar,  starch,  fibrin,  gelatin,  albumin, 
etc.  By  the  action  of  potash  upon  chloroform  and  kindred  bodies.  By 
the  action  of  mineral  acids  on  hydrocyanic  acid.  During  the  fermentation 
of  diabetic  urine.  By  the  direct  union  of  carbon  monoxide  and  water: 

CO  +  H30=C02H2. 

By  the  decomposition  of  oxalic  acid  under  the  influence  of  glycerin  at 
about  100°: 

C204H2     =     C02     +     C02Ha. 

The  last  is  the  reaction  utilized  in  obtaining  formic  acid. 

It  is  a  colorless  liquid,  having  a  sharp,  acid  taste,  and  a  penetrating 
odor;  when  brought  in  contact  with  the  skin  it  acts  as  a  vesicant;  it  boils 
at  100°  at  the  normal  barometric  pressure,  and,  when  pure,  crystallizes  at 
0°;  it  is  miscible  with  water  in  all  proportions. 

The  mineral  acids  decompose  it  into  water  and  carbon  monoxide; 
oxidizing  agents  convert  it  into  water  and  carbon  dioxide;  alkaline  hy- 
drates decompose  it  with  formation  of  a  carbonate  and  liberation  of  hy- 
drogen; it  acts  as  a  reducing  agent  with  the  salts  of  the  noble  metals. 


ACETIC   ACID.  185 

Acetic  Acid. 

Acetyl  hydrate — Hydrogen  acetate — Pyroligneous  acid — Acidum  aceti- 
cum  (U.  S.,  Br.)  — CaH3O3H—°»H^  io.— Although  in  its  dilute  form, 

as  vinegar,  it  has  been  known  from  remote  antiquity,  the  pure  acid  was 
only  obtained  in  the  last  century. 

It  is  produced  in  a  great  number  of  reactions,  the  principal  of  which 
are  : 

First. — By  the  oxidation  of  alcohol : 

CaH60  +  Oa=CaH4Oa+H30. 

Second. — By  the  dry  distillation  of  wood. 

Third. — By  the  decomposition  of  natural  acetates  by  mineral  acids. 

Fourth. — By  the  action  of  potash  in  fusion  on  sugar,  starch,  oxalic, 
tartaric,  citric  acids,  etc. 

Fifth. — By  the  decomposition  of  gelatin,  fibrin,  casein,  etc.,  by  sul- 
phuric acid  and  manganese  dioxide. 

Sixth. — By  the  action  of  carbon  dioxide  upon  sodium  methyl : 

C02  +  NaCH8=CaH3OaNa, 

and  decomposition  of  the  sodium  acetate  so  produced. 

The  acetic  acid  used  in  the  arts  and  in  pharmacy  is  prepared  by  the 
destructive  distillation  of  wood,  which  is  heated  in  an  iron  retort  con- 
nected with  a  condensing  system.  The  products  of  the  distillation, 
which  vary  with  the  nature  of  the  wood  used,  are  numerous.  Charcoal 
remains  in  the  retort,  while  the  distilled  product  consists  of  an  acid, 
watery  liquid,  a  tarry  material,  and  gaseous  products.  One  hundred 
>arts  of  wood  yield  usually: 

Charcoal 28 — 30  parts. 

Acid  water 23 — 30  parts. 

Tar 7—10  parts. 

Gas 37 — 30  parts. 


The  gases  are  carbon  dioxide,  carbon  monoxide,  and  hydrocarbons;  they 
are  sometimes  used  for  illuminating  purposes,  but  are  usually  directed 
into  the  furnace,  where  they  serve  as  fuel.  The  tar  is  a  mixture  of  em- 
pyreumatic  oils,  hydrocarbons,  phenol,  oxyphenol,  acetic  acid,  ammonium 
acetate,  etc.,  and  is  used  almost  exclusively  for  the  preservation  of  cord- 
age and  wood  in  ships. 

The  acid  water  is  very  complex,  and  contains,  besides  acetic  acid, 
formic,  propionic,  butyric,  valerianic,  and  oxyphenic  acids,  acetone,  naph- 
thalene, benzene,  toluene,  cumene,  creasote,  methyl  alcohol,  and  methyl 
acetate,  etc.  Partially  freed  from  tar  by  decantation,  it  is  a  brown,  acid 
liquid,  having  a  disagreeable,  empyreumatic  odor.  It  still  contains  about 
twenty  per  cent,  of  tarry  and  oily  material,  and  about  four  per  cent,  of 
acetic  acid;  this  is  the  crude pyroligneous  acid  of  commerce. 

The  crude  product  is  subjected  to  a  first  purification  by  distillation; 
the  first  portions  are  collected  separately  and  yield  meth}'-!  alcohol  (q.  v.)\ 
the  remainder  of  the  distillate  is  the  distilled  pyroligneous  acid  of  com- 


186 


GENERAL    MEDICAL   CHEMISTRY. 


merce,  used  to  a  limited  extent  as  an  antiseptic,  but  principally  for  the 
manufacture  of  acetic  acid  and  the  acetates.  It  can  only  be  freed  from  the 
impurities  which  it  still  contains  by  chemical  means;  to  this  end  slacked 
lime  and  chalk  are  added,  at  a  gentle  heat,  to  neutralization;  the  liquid 
is  boiled  and  allowed  to  settle1  twenty -four  hours;  the  clear  liquid,  which 
is  a  solution  of  calcium  acetate,  is  decanted  and  evaporated;  the  calcium 
salt  is  converted  into  sodium  acetate,  which  is  then  purified  by  calcina- 
tion at  a  temperature  below  030°,  dissolved,  filtered,  and  recrystallized; 
the  salt  is  then  decomposed  by  a  proper  quantity  of  sulphuric  acid,  and 
the  liberated  acetic  acid  separated  by  distillation. 

The  product  so  obtained  is  a  solution  of  acetic  acid  in  water,  contain- 
ing thirty-six  per  cent,  of  true  acetic  acid,  and  being  of  sp.  gr.  1.047, 
United  States  (the  acid  of  the  British  Pharmacopoeia  is  weaker — thirty- 
three  per  cent.,  C2H4O2,  and  sp.  gr.  1.044). 

When  pure  acetic  acid  is  required,  recourse  is  had  to  the  decomposi- 
tion of  a  dry  acetate  by  heat;  it  is  known  as  glacial  acetic  acid. 

Acetic  acid  is  a  colorless  liquid  at  ordinary  temperatures;  below  17°, 
when  pure,  it  is  a  crystalline  solid.  It  boils  at  119°;  sp.  gr.  1.0801  atO°; 
its  odor  is  penetrating  and  acid;  when  brought  in  contact  with  the  skin 
it  destroys  the  epidermis  and  causes  vesication;  it  mixes  with  water  in  all 
proportions,  the  mixtures  being  less  in  volume  than  the  sum  of  the  volumes 
of  the  constituents.  The  specific  gravities  of  the  mixtures  gradually  in- 
crease up  to  that  containing  twenty-three  per  cent,  of  water,  after  which 
they  again  diminish,  and  all  the  mixtures  containing  more  than  forty- 
three  per  cent,  of  acid  are  of  higher  specific  gravity  than  the  acid  itself. 
In  the  following  table  are  given  the  specific  gravity  of  acids  of  different 
degrees  of  concentration  at  15°  C.: 


Acetic  acid, 
per  cent. 

Specific 
gravity. 

Acetic  acid, 
per  cent. 

Specific 
gravity. 

Acetic  acid, 
per  cent. 

Specific 
gravity. 

Acetic  acid, 
per  cent. 

Specific 
gravity. 

0 

0.9992 

26 

1.0363 

51 

1.0623 

76 

1.0747 

1 

.0007 

27 

1.0375 

52 

1.0631 

77 

1.0748 

2 

.0022 

28 

1.0388 

53 

1.0638 

78 

1.0748 

3 

.0037 

29 

1.0400 

54 

1.0646 

79 

1.0748 

4 

.0052 

30 

1.0412 

55 

1.0653 

80 

1.0748 

5 

.0067 

31 

1.0424 

56 

1.0660 

81 

1.0747 

6 

.0083 

32 

1.0436 

57 

1.0666 

82 

1.0746 

7 

.0098 

33 

1.0447 

58 

1.0673 

83 

1.0744 

8 

.0113 

34 

1.0459 

59 

1.0679 

84 

1.0742 

9 

.0127 

35 

1.0470 

60 

1.0685 

85 

1.0739 

10 

.0142 

36 

1.0481 

61 

1.0691 

86 

1.0736 

11 

.0157 

37 

1.0492 

62 

1.0697 

87 

1.0731 

12 

.0171 

38 

1.0502 

63 

1.0702 

88 

1.0726 

13 

.0185 

39 

1.0513 

64 

1.0707 

89 

1.0720 

14 

.0200 

40 

1.0523 

65 

1.0712 

90 

1.0713 

15 

.0214 

41 

1.0533 

66 

1.0717 

91 

.0705 

16 

.0228 

42 

1.0543 

67 

1.0721 

92 

.0696 

17 

.0242 

43 

1.0552 

68 

1.0725 

93 

.0686 

18 

.0256 

44 

1.0562 

69 

1.0729 

94 

.0674 

19 

.0270 

45 

1.0571 

70 

1.0733 

95 

.0060 

20 

.0284 

46 

1.0580 

71 

1.0737 

96 

.0644 

21 

.0298 

47 

1.0589 

72 

1.0740 

97 

.0625 

22 

1.0311 

48 

1.0598 

73 

1.0742 

98 

.0604 

23 

1.0824 

49 

1.0607 

74 

1.0744 

99 

.0580 

24 

1.0337 

50 

1.0615 

75 

1.0746 

100 

1.0553 

25 

1.0350 

ACETIC    ACID.  187 

The  vapor  of  acetic  acid  burns  with  a  pale,  bluish  flame;  when  passed 
through  a  tube  heated  to  redness  it  is  decomposed,  a  mixture  of  combus- 
tible gases  being  given  off  and  a  carbonaceous  residue  remaining  in  the 
tube.  The  pure  acid  only  decomposes  calcic  carbonate  when  diluted  with 
water;  and  when  mixed  with  alcohol  does  not  redden  litmus  paper. 

Sulphuric  acid,  aided  by  heat,  decomposes  and  blackens  acetic  acid; 
sulphur  and  carbon  dioxides  are  given  off.  The  presence  of  acetic  acid 
may  be  recognized  by  this  and  by  the  following  reactions:  with  silver 
nitrate,  a  white,  cr3Tstalline  precipitate,  partially  dissolved  by  heat;  no 
reduction  of  silver  on  boiling  the  mixture.  When  it  is  heated  with  small 
quantities  of  alcohol  and  sulphuric  acid,  acetic  ether  is  given  off,  and  may 
be  recognized  by  its  odor.  When  an  acetate  is  calcined  with  a  small  Quan- 
tity of  arsenic  trioxide,  the  foul  odor  of  cacodyl  oxide  is  observed. 

Chlorine  acts  upon  acetic  acid  slowly  under  ordinary  conditions,  but 
actively  under  the  influence  of  direct  sunlight,  producing  monochlor- 
acetic  acid,  C2H3C1O2;  dichloracetic  acid,  C2H2C12O2;  and  trichlor  acetic 
acid,  C2HC13O2.  The  last-named  is  obtained  by  exposing  glass-stoppered 
bottles  (well  closed)  filled  with  dry  chlorine,  and  containing  a  small  quan- 
tity of  glacial  acetic  acid,  to  the  direct  rays  of  the  sun  for  a  day  or  more. 
It  it  an  odorless,  crystalline  solid,  which  fuses  at  4G°,  and  distils  at  195° — 
200°.  It  is  strongly  acid,  and  has  been  used  in  medical  practice  as  a  pow- 
erful vesicant. 

Acetic  acid  is  used  in  pharmacy  in  the  preparation  of  many  sub- 
stances. The  Acidum  aceticum  dilutum  (U.  S.,  Br.)  is  of  sp.  gr.  i.OOG, 
and  contains  4.5  per  cent,  of  true  acetic  acid;  its  chief  use  is  in  the  prep- 
aration of  the  aceta  or  medicated  vinegars,  improperly  so  called,  which, 
whether  they  be  made  with  dilute  acetic  acid,  or  with  distilled  vinegar, 
do  not  contain  those  constituents  of  vinegar  which  distinguish  it  from  di- 
lute acetic  acid. 

Vinegar  is  an  acid  liquid  owing  its  acidity  to  acetic  acid,  and  hold- 
ing certain  fixed  and  volatile  substances  in  solution.  It  has  been  known 
from  early  antiquity,  and  was  the  only  acid  known  up  to  the  end  of  the 
eighth  century,  when  the  Arabian  alchemist  Djafar,  or  Geber,  as  he  is  fre- 
quently called,  discovered  nitric  acid. 

It  is  obtained  from  some  liquid  containing  ten  per  cent,  or  less  of 
alcohol,  which  is  converted  into  acetic  acid,  either  by  simple  oxidation, 
as  under  the  influence  of  platinum  black,  or,  as  in  the  industrial  manufac- 
ture of  vinegar,  by  the  transferring  of  atmospheric  oxygen  to  the  alcohol 
during  the  process  of  nutrition  of  a  peculiar  vegetable  ferment,  known  as 
mycoderma  aceti  or,  popularly,  as  mother  of  vinegar.  Vinegar  is  now 
manufactured  principally  by  one  or  two  processes — the  German  method 
and  that  of  Pasteur.  In  the  former,  the  alcoholic  fluid,  which  must  also 
contain  albuminous  matter,  is  allowed  to  trickle  slowly  through  barrels  in 
which  it  meets  near  the  top  a  diaphragm,  pierced  with  a  number  of  holes, 
through  which  pass  short  cords;  from  these  it  drops  upon  a  thick  layer 
of  beech-wood  shavings,  supported  by  a  perforated  false  bottom.  By  a 
suitable  arrangement  of  holes  and  tubes,  an  ascending  current  of  air  is 
made  to  pass  through  the  barrel.  The  acetic  ferment  clings  to  the 
cords  and  shavings,  and  under  its  influence  acetification  takes  place  rap- 
idly, owing  to  the  large  surface  exposed  to  the  air. 

In  Pasteur's  process,  which  has  to   a  great   extent   superseded  the 

Erocess  formerly  followed  at  Orleans,  the  ferment  is  sown  upon  the  sur- 
ice  of  the    alcoholic    liquid,  contained   in  large,  shallow,  covered  vats, 
from  which  the  vinegar  is  drawn  off  after  acetification  has  been  com- 


188  GENERAL    MEDICAL    CHEMISTRY. 

pleted  ;    the   mother   is    collected,  washed,    and    used   in    a  subsequent 
operation. 

The  liquids  from  which  vinegar  is  made  are  wine,  cider,  and  beer,  to 
which  dilute  alcohol  is  frequently  added;  the  most  esteemed  being  that 
obtained  from  white  wine. 

Wine  vinegar  has  a  pleasant,  acid  taste  and  odor;  it  consists  of  water, 
acetic  acid  (about  five  per  cent.),  potassium  bitartrate  (about  2.5  grams 
per  litre),  alcohol,  acetic  ether,  glucose,  malic  acid,  mineral  salts  present 
in  wine,  a  fermentescible,  nitrogenized  substance,  coloring  matter,  etc. 
Its  specific  gravity  is  1.020  to  1.025;  its  color  varies  from  a  pale  yellow  to 
a  light  reddish  brown,  according  as  it  is  made  from  white  or  red  wine. 
When  evaporated,  it  yields  from  1.7  to  2.4  per  cent,  of  solid  residue. 

Vinegars  made  from  alcoholic  liquids  other  than  wine  contain  no  po- 
tassium bitartrate,  contain  less  acetic  acid,  and  have  not  the  aromatic 
odor  of  wine  vinegar.  Cider  vinegar  is  of  sp.  gr.  2.0;  is  yellowish,  has 
an  odor  of  apples,  and  yields  1.5  per  cent,  of  extract  on  evaporation. 
Beer  vinegar  is  of  sp.  gr.  3.2;  has  a  bitterish  flavor,  and  an  odor  of  sour 
beer;  it  leaves  six  per  cent,  of  extract  on  evaporation. 

The  principal  adulterations  of  vinegar  are:  sulphuric  acid,  whose 
presence  is  indicated  by  an  increase  in  the  specific  gravity,  or  more  cer- 
tainly, by  adding  a  few  drops  of  the  vinegar  to  some  fragments  of  cane- 
sugar,  and  evaporating  over  the  water-bath  to  dryness;  in  the  presence 
of  sulphuric  acid  the  residue  is  dark  brown  or  black.  As  commercial 
sulphuric  acid  always  contains  arsenic,  that  element  has  frequently  been 
detected  in  adulterated  vinegars.  Water,  an  excess  of  which  is  indicated 
by  a  low  power  of  saturation  of  the  vinegar,  in  the  absence  of  mineral 
acids.  Two  parts  of  good  wine  vinegar  neutralize  ten  parts  of  sodium 
carbonate;  the  same  quantity  of  cider  vinegar,  3.5  parts;  and  of  beer  vine- 
gar, 2.5  parts  of  carbonate.  Pyroligneous  acid  may  be  detected  by  the 
creosote-like  odor  and  taste.  Pepper,  capsicum,  and  other  acrid  substan- 
ces, are  often  added  to  communicate  fictitious  strength;  in  vinegar  so 
adulterated  an  acrid  odor  is  perceptible  after  neutralization  of  the  acid 
with  sodium  carbonate.  Copper,  zinc,  lead,  and  tin  frequently  occur 
in  vinegar  which  has  been  in  contact  with  those  elements,  either  during 
the  process  of  manufacture  or  subsequently;  they  may  be  detected  by 
methods  elsewhere  described. 

Distilled  vinegar,  Acetum  destillatum  (U.  S.),  is  prepared  by  distilling 
vinegar  in  glass  vessels;  it  contains  none  of  the  fixed  ingredients  of  vine- 
gar, but  its  volatile  constituents  (acetic  acid,  water,  alcohol,  acetic  ether, 
odorous  principles,  etc.),  and  a  small  quantity  of  aldehyde.  It  is  a  limpid, 
wholly  volatile  liquid,  whose  odor  is  similar  to,  but  weaker  than  that  of 
the  kind  of  vinegar  from  which  it  was  distilled,  from  which  it  also  differs 
in  being  of  less  acid  strength,  as  the  boiling-point  of  acetic  acid  is  higher 
than  that  of  water.  Dilute  acetic  acid  is  frequently  called  distilled  vinegar. 

When  dry  acetate  of  copper  is  distilled,  a  blue,  strongly  acid  liquid 
passes  over;  this,  upon  rectification,  yields  a  colorless,  mobile  liquid, 
which  boils  at  56°  C.,  has  a  peculiar  odor,  and  is  a  mixture  of  acetic 
acid,  water,  and  acetone,  known  to  the  older  chemists  as  radical  vinegar, 
and  still  used  under  that  name  in  perfumery. 

Toxicology. — When  taken  internally,  acetic  acid  and  vinegar  (the 
latter  in  doses  of  four  to  five  fl.  3  )act  as  irritants  and  corrosives,  causing 
in  some  instances  perforation  of  the  stomach,  and  death  in  from  six  to 
fifteen  hours.  Milk  of  magnesia  should  be  given  as  an  antidote,  with  the 
view  to  neutralizing  the  acid. 


BUTYRIC    ACID.  189 

The  presence  of  acetic  acid,  or  of  an  acetate,  may  be  recognized  by 
the  following  tests : 

First. — When  heated  with  sulphuric  acid,  acetic  acid,  recognizable 
by  its 'odor,  is  given  off. 

Second. — If  a  mixture  of  an  acetate,  sulphuric  acid,  and  alcohol  be 
heated,  the  apple  odor  of  ethyl  acetate  is  produced. 

Third. — Neutral  solution  of  ferric  chloride  forms,  with  a  neutral  solu- 
tion of  an  acetate,  a  deep  red  liquid,  which  turns  yellow  on  the  addition 
of  a  free  acid. 


Propionic  Acid,  C8H6Oa— ^^  1  O. 

This  acid,  discovered  by  Gottlieb  in  1844,  is  formed  in  many  decom- 
positions of  organic  substances.  By  the  action  of  caustic  potassa  upon 
sugar,  starch,  gum,  and  ethyl  cyanide;  during  fermentation,  vinous  or 
acetic,  in  wine,  moist  leather,  calcium  tartrate  solution;  in  the  distillation 
of  wood,  and  during  the  putrefaction  of  peas,  beans,  etc.;  by  the  oxida- 
tion of  normal  propylic  alcohol,  etc.  It  is  best  prepared  by  heating 
ethyl  cyanide  with  potash  until  the  odor  of  the  ether  has  disappeared; 
the  acid  is  then  liberated  from  its  potassium  compound  by  sulphuric  or 
phosphoric  acid,  and  purified. 

It  is  a  colorless  liquid,  sp.  gr.  0.996,  does  not  solidify  at  — 21°,  boils 
at  140°,  mixes  with  water  and  alcohol  in  all  proportions,  resembles  acetic 
acid  in  odor  and  taste.  Its  salts  are  soluble  and  crystallizable. 

Propionic  acid  is  probably  formed  in  the  body  as  a  product  of  oxida- 
tion of  the  fats  and  albuminoids,  its  presence,  however,  has  not  been 
demonstrated  with  certainty,  although  it  has  been  said  to  exist  in  the 
perspiration,  the  contents  of  the  stomach,  in  the  vomit  of  cholera,  and  in 
fermented  diabetic  urine. 


Butyric  Acid,     *    'jj  [  O CH3— CHa— CHa— CO,OH. 

Discovered  by  Chevreul  in  butter;  it  exists  in  nature  free  and  in  com- 
bination, in  its  ethylic  and  glyceric  ethers.  It  has  been  found  in  the 
milk,  perspiration,  muscular  fluid,  the  juices  of  the  spleen  and  of  other 
glands,  the  urine,  contents  of  the  stomach  and  large  intestine,  faeces,  and 
guano,  in  certain  fruits,  in  yeast,  in  the  products  of  decomposition  of 
many  vegetable  substances,  and  in  natural  waters;  in  fresh  butter  in 
small  quantity,  more  abundantly  in  that  which  is  rancid. 

It  is  formed  in  a  number  of  decompositions  of  organic  substances. 
By  the  action  of  sulphuric  acid  and  manganese  dioxide,  aided  by  heat, 
upon  cheese,  starch,  gelatin,  etc.;  during  the  combustion  of  tobacco  (as 
ammonium  butyrate);  by  the  action  of  nitric  acid  upon  oleic  acid;  during 
the  putrefaction  of  fibrin  and  other  albuminoids;  during  a  peculiar  fer- 
mentation of  glucose  and  starchy  material  in  the  presence  of  casein  or 
gluten.  This  fermentation,  known  as  the  butyric,  takes  place  in  two 
stages;  at  first  the  glucose  is  converted  into  lactic  acid: 

C.H,,0,=2(C,H,0,), 


190  GENERAL   MEDICAL    CHEMISTRY. 

and  this  in  turn   is   decomposed   into  butyric   acid,  carbon  dioxide,  and 
hydrogen  : 


Butyric  acid  is  now  usually  obtained  from  the  animal  charcoal  which 
has  been  used  in  the  purification  of  glycerine,  in  which  it  exists  as  cal- 
cium butyrate.  It  is  also  formed  by  subjecting  to  fermentation,  at  25°  — 
30°,  a  mixture  composed  of  glucose  1  kilo,  water  to  sp.  gr.  10°  Baume, 
chalk  0.5  kilo,  cheese  or  gluten  0.1  kilo.  The  calcium  butyrate  is  de- 
composed by  sulphuric  acid,  and  the  butyric  acid  separated  by  distilla- 
ation. 

Butyric  acid  is  a  colorless,  mobile  liquid,  having  a  disagreeable,  persis- 
tent odor  of  rancid  butter,  and  a  sharp,  acid  taste,  soluble  in  water,  alcohol. 
ether,  and  methyl  alcohol;  boils  at  164°,  distilling  unchanged;  solidifies  in 
a  mixture  of  solid  carbon  dioxide  and  ether;  sp.  gr.  0.974  at  15°;  a  good 
solvent  of  fats. 

Sulphuric  acid  does  not  act  upon  butyric  acid  in  the  cold,  and  only 
slightly  under  the  influence  of  heat.  Nitric  acid  dissolves  it  unaltered  in 
the  cold,  but,  on  the  application  of  heat,  oxidizes  it  to  succinic  acid.  Dry 
chlorine  under  the  influence  of  sunlight,  and  bromine  under  the  influence 
of  heat  and  pressure,  form  products  of  substitution  with  butyric  acid.  It 
readily  forms  ethers  and  salts,  the  latter  being,  for  the  most  part,  soluble 
in  water.  Its  vapor  is  inflammable  and  burns  with  a  blue  flame. 

Butyric  acid  is  formed  in  the  intestine,  by  the  process  of  fermentation 
mentioned  above,  at  the  expense  of  those  portions  of  the  carbohydrate 
elements  of  food  which  escape  absorption,  arid  is  discharged  with  the 
faeces  as  ammonium  butyrate. 

Isobutyric  acid,  an  isomere  of  butyric  acid,  which  boils  at  152°,  has 
also  been  found  in  human  faeces.  It  corresponds  to  isobutyl  alcohol,  and 
has  the  composition  — 

3CH—  CO>OH- 


Valerianic  Acids,  C5HIOO2—  C*H»°  i  O. 

Corresponding  to  the  four  primary  amylic  alcohols,  there  are  four 
amylic  or  valerianic  acids: 

I.  CH3—  CH2—  CH2—  CH2—  CO,OH. 
II.         3CH~~  CH'~~  CO>OH- 


-  CHS 


IV.  CH  —  C—  CO,OH. 
CH3/ 


CAPROIO    ACIDS.  191 

T.  Normal  valerianic  acid — Butylformic  acid — Propylacetic  acid — 
is  obtained  by  the  oxidation  of  normal  amylic  alcohol.  It  is  an  oily  liquid, 
boils  at  184° — 185°,  and  has  an  odor  resembing  that  of  butyric  acid. 

II.,  III.  Ordinary  valerianic  acid — Delphinic  acid — Phocenic  acid 
— Isovaleric  acid — Isopropyl  acetic  acid — Isobutylformic  acid — Acidum 
valerianicum  (U.  S.,  Br.). — This  acid  was  discovered  in  1817  by  Chevreul, 
in  the  oil  of  the  porpoise  (delphinium  phocoena),  and  subsequently  in  vale- 
rian root  and  in  angelica  root.  It  is  formed  during"  putrid  fermentation  or 
oxidation  of  albuminoid  substances.  It  occurs  in  the  urine  and  faeces  in  ty- 
phus, variola,  and  acute  atrophy  of  the  liver.  It  is  also  formed  in  a  variety 
of  chemical  reactions  and  notably  by  the  oxidation  of  amylic  alcohol. 

It  is  prepared  either  by  distilling  water  from  valerian  root,  or,  moro 
economically,  by  mixing  rectified  amylic  alcohol  with  sulphuric  acid, 
adding,  when  cold,  a  solution  of  potassium  dichromate,  and  distilling 
after  the  reaction  has  become  moderated;  the  distillate  is  neutralized  with 
sodium  carbonate;  and  the  acid  is  obtained  from  the  sodium  valerianate 
so  produced,  by  decomposition  by  sulphuric  acid  and  rectification. 

The  properties  and  nature  of  the  acid  differ  according  to  those  of  the 
amyl  alcohol  from  which  it  is  obtained.  The  active  alcohol  yields  the  acid, 

— CH2— CO,OH, 

which  is  itself  optically  active,  which  forms  an  uncrystallizable  and  ex- 
ceedingly soluble  barium  salt,  and  whose  boiling-point  is  172.5° — 173.5°. 

OT-J  \ 
The   inactive  alcohol    yields    by  oxidation  the    acid,  prr prr3  /CH — 

CO, OH,  which  is  optically  inactive,  whose  barium  salt  is  readily  crystalliz- 
able  and  soluble  in  water  to  the  extent  of  forty-eight  parts  in  one  hun- 
dred, and  whose  boiling-point  is  174.5°. 

The  identity  of  the  acid  obtained  from  valerian  root  and  that  obtained 
by  the  oxidation  of  amylic  alcohol  has  frequently  been  called  in  question. 
The  properties  of  the  former  show,  however,  that  it  is  identical  with  the 
acid  obtained  by  the  oxidation  of  optically  inactive  amylic  alcohol.  The 
artificial  product,  being  obtained  from  the  commercial  mixture  of  active 
and  inactive  alcohols,  is  a  mixture  in  different  proportions  of  the  two  acids 
mentioned  above. 

The  ordinary  valerianic  acid  is  an  oily,  colorless  liquid,  having  a  pene- 
trating odor,  and  a  sharp,  acrid  taste.  It  solidifies  at  —16°;  boils  at  173° 
—175°;  sp.  gr.  0.9343 — 0.94fi5  at  20°;  burns  with  a  white,  smoky  flame. 
It  dissolves  in  thirty  parts  of  water,  and  in  alcohol  and  ether  in  all  propor- 
tions. It  dissolves  phosphorus,  camphor.,  and  certain  resins.  It  forms 
salts  and  ethers  called  valerianates,  some  of  which,  as  those  of  ammonium, 
zinc,  quinine,  atropine,  bismuth,  and  iron,  are  used  in  medicine. 

IV.  Trimethyl  acetic  acid — Pivalic  acid — is  a  crystalline  solid,  which 
fuses  at  35.5°  and  boils  at  163.7°;  sparingly  soluble  in  water;  obtained 
by  the  action  of  cyanide  of  mercury  upon  tertiary  butyl  iodide. 

Caproic  Acids. 

Hexylic  acids— C6H12O2— C«H"^  i  O.— There  probably  exist  quite  a 

number  of  isomeres  having  the  composition  indicated  above,  some  of 
which  have  been  prepared  from  butter,  cocoa-oil,  and  cheese,  and  by  de- 
composition of  amyl  cyanide,  or  of  hexyl  alcohol. 


i 


192  GENERAL    MEDICAL    CHEMISTRY. 

The  acid  obtained  from  butter,  in  which  it  exists  as  a  glyceric  ether, 
is  a  colorless,  oily  liquid,  boils  at  205°;  sp.  gr.  0.931  at  15°;  has  an  odor 
of  perspiration  and  a  sharp,  acid  taste;  is  very  sparingly  soluble  in  water, 
but  soluble  in  alcohol.  The  acid  obtained  from  amyl  cyanide  deviates 
the  plane  of  polarization  to"  the  right;  ([«]r  =  2.43°);  boils  at  198°,  and 
solidifies  at  —9°. 

CEnanthylic  Acid. 

O  H    O  ) 

Ileptylic  acid,  C,H14Oa —   7     13rr  !•  O — exists  in  spirits  distilled   from 

rice  and  maize,  and  is  formed  by  the  action  of  nitric  acid  upon  fatty  sub- 
stances, especially  upon  castor  oil.  It  is  a  colorless  oil;  boils  at  212°; 
sp.  gr.  0.9167  at  24°;  soluble  in  alcohol  and  in  ether. 

Caprylic  Acid. 

O  H   O  ) 

Octylic  acid,  C8H18Oa —  8  15j^  v  O — accompanies  caproic  acid  in  but- 
ter, cocoa-oil,  etc.  It  is  solid,  melts  at  14° — 15°,  and  boils  at  236°;  almost 
insoluble  in  water;  very  soluble  in  alcohol  and  in  ether. 

Pelargonic  Acid. 

Nonylic  acid,  C9H18O2— CoH'^  I  Q— exists  in  the  volatile  oil  of  ge- 
ranium, and  is  formed  by  the  action  of  nitric  acid  upon  essence  of  rue. 
It  is  a  colorless  oil;  has  a  feeble  odor;  solidifies  at  10°;  boils  at  260°;  in- 
soluble in  water;  soluble  in  alcohol  and  ether. 

Capric  Acid. 

OHO) 
Decylic  acid,  CtoH^Ot —   10    19jj  >  O — exists  in  butter,  cocoa-oil,  etc., 

associated  with  caproic  and  caprylic  acids  in  their  glyceric  ethers,  and  in 
the  residues  of  distillation  of  Scotch  whiskey,  as  amyl  caprate.  It  is  a 
white,  crystalline  solid;  melts  at  27.5°;  boils  at  273°;  insoluble  in  water; 
soluble  in  alcohol  and  ether;  has  a  faint  odor,  resembling  that  of  the  goat. 

Laurie  Acid. 

OHO) 
Laurostearic  acid,  C12H24O3 —   12    "H  j-  O — exists   in  laurel    berries, 

cocoa-butter,  and  in  other  vegetable  fats.  It  is  a  transparent,  crystalline 
solid;  melts  at  43.5°;  insoluble  in  water;  readily  soluble  in  alcohol  and 
in  ether. 

Myristic  Acid,  C14H2809— °"H"jj  j-  O, 

Exists  in  many  vegetable  oils,  in  cow's  butter,  and  in  spermaceti.  It 
crystallizes  in  brilliant,  colorless  plates;  fusible  at  54°. 


STEARIC    ACID.  193 


Palmitic  Acid. 

C1   TT  O  ) 

Ethalic  acid,  C16H32Oa —  16  31H  V  O— exists  in  palm-oil,  in  combi- 
nation when  the  oil  is  fresh,  and  free  when  the  oil  is  old;  it  also  enters 
into  the  composition  of  nearly  all  animal  and  vegetable  fats.  It  is  ob- 
tained from  the  fats,  palm-oil,  etc.,  by  saponification  with  caustic  potassa 
(see  p.  285),  and  subsequent  decomposition  of  the  soap  by  a  strong  acid. 
It  is  also  formed  by  the  action  of  caustic  potash  in  fusion  upon  cetyl 
alcohol  (ethal),  and  by  the  action  of  the  same  reagent  upon  oleic  acid. 

Palmitic  acid  is  a  white,  crystalline  solid;  odorless;  tasteless;  lighter 
than  water,  in  which  it  is  insoluble;  quite  soluble  in  alcohol  and  in  ether; 
fuses  at  62°;  distils  unchanged  with  vapor  of  water.  It  is  used  in  the 
manufacture  of  candles  and  of  soaps. 

Margaric  Acid,  C17H34O2— C"H-°  I  O. 

Previous  to  1852  this  acid  was  supposed  to  exist  as  a  glyceride  in  all 
fats,  solid  and  liquid;  in  that  year,  however,  Heintz  showed  that  what  had 
been  taken  for  margaric  acid  was  a  mixture  of  ninety  per  cent,  of  palmitic 
and  ten  per  cent,  of  stearic  acid,  and  at  the  same  time  he  obtained  the 
true  margaric  acid  by  the  action  of  potassium  hydrate  upon  cetyl  cyanide. 

It  is  a  white,  crystalline  body;  fusible  at  59.9°;  insoluble  in  water; 
soluble  in  alcohol  and  in  ether. 


Stearic  acid,  C18H36O— C»H««°  I  O. 


P. 


This,  the  most  abundant  of  the  fatty  acids,  was  discovered  by  Chevreul 
in  1811.  It  exists  as  a  glyceride  in  all  solid  fats,  and  in  many  oils,  and 
also  free  to  a  limited  extent. 

To  obtain  it  pure,  the  fat  is  saponified  with  an  alkali,  and  the  soap  de- 
composed by  hydrochloric  acid;  the  mixture  of  fatty  acids  is  dissolved  in 
a  large  quantity  of  alcohol,  and  the  boiling  solution  partly  precipitated  by 
the  addition  of  a  concentrated  solution  of  barium  acetate.  The  precip- 
itate is  collected,  washed,  and  decomposed  by  hydrochloric  acid;  the 
stearic  acid  which  separates  is  washed  and  recrystallized  from  alcohol. 
The  process  is  repeated  until  the  product  fuses  at  70°. 

An  impure  stearic  acid,  mixed  with  palmitic  and  other  acids,  is  pre- 
red  industrially  on  a  large  scale  in  the  manufacture  of  stearin  candles. 

Pure  stearic  acid  is  a  colorless,  odorless,  tasteless  solid;  fusible  at  69° 
—70°;  unctuous  to  the  touch;  insoluble  in  water;  very  soluble  in  alcohol 
and  in  ether.  The  alkaline  stearates  are  soluble  in  water;  those  of  cal- 
cium, barium,  and  lead  are  insoluble. 

Stearic  and  palmitic  acids  exist  free  in  the  intestine  during  the  diges- 
tion of  fats,  a  portion  of  which  is  decomposed  by  the  action  of  the  pan- 
creatic secretion  into  fatty  acids  and  glycerin.  The  same  decomposition 
also  occurs  in  the  presence  of  putrefying  albuminoid  substances. 

P    TT  *O  ) 

Arachic  acid,  C30H40Oa—    20    3Vr  [•  O — exists  as  a  glyceride  in  pea- 
nut-oil (now  largely  used  as  a  substitute  for  olive-oil),  in  oil  of  ben,  and 
13 


194  GENERAL    MEDICAL    CHEMISTRY. 

in  small  quantity  in  butter.  It  is  a  crystalline  solid,  which  melts  at  75°, 
and  solidifies  at  73°;  sparingly  soluble  in  aqueous  alcohol;  soluble  in  ab- 
solute alcohol  and  ether. 

O  TT   O  ) 

Benic  acid — Benostearic  acid—  C22H44Oa—  22  ^  !•  O— a  solid,  crys- 
talline body;  fuses  at  76°:  solidifies  at  70°;  exists  in  oil  of  ben. 

Hyaenic  acid,  C26H60O2— C"H«O  j.  Q— exists  in  the  fat,  and  espe- 
cially in  the  anal  glands,  of  the  hyena. 

O   TT   O  ) 
Cerotic  acid,  C27H64O2—    27    B3g  j-  O — constitutes  the  bulk  of  that 

part  of  beeswax  which  is  soluble  in  boiling  alcohol,  and  may  be  obtained 
from  China  wax  by  dry  distillation. 

Melissic  acid,  C30H60Oa—    30    B9g  i  O — exists  in  beeswax. 

COMPOUND  ETHERS. 
Methylic. 

Methyl  nitrate,  prr3  j-  O — is  prepared  by  bringing  together,  in  a 

retort,  powdered  potassium  nitrate  and  a  mixture  of  sulphuric  acid  and 
methyl  alcohol;  the  action  takes  place  at  first  in  the  cold,  but  the  distil- 
lation must  be  completed  at  the  temperature  of  the  water-bath.  The  dis- 
tillate is  purified  by  washing  with  water,  and  by  repeated  rectifications 
from  massicot  and  calcium  chloride. 

It  is  a  colorless  liquid;  sp.  gr.  1.182  at  22°;  boils  at  66°;  burns  with 
a  yellow  flame;  its  vapor  detonates  violently  when  heated  above  150°.  It 
is  decomposed  by  potash  into  potassium  nitrate  and  methylic  alcohol;  it 
dissolves  ammpnia,  with  formation  of  ammonium  nitrate  and  methylamine. 
It  is  a  good  solvent  of  nitro-glycerine  and  of  gun-cotton. 

Methyl  nitrite,  QTT   [  O — is  obtained  by  heating  methylic  alcohol 

•with  nitric  acid  and  copper.  Below  — 12°  it  is  a  yellowish  liquid;  above 
that  temperature,  a  gas.  Isomeric  with  nitromethane. 


Ethylic. 


Ethyl  nitrate  —  Nitric  ether  —  O—  is  obtained  by  distilling  a 

mixture  of  one  volume  of  nitric  acid  and  two  volumes  of  alcohol,  in  the  pres- 
ence of  urea,  the  last-named  substance  being  added  to  prevent  the  forma- 
tion of  the  lower  oxides  of  nitrogen.  The  first  part  of  the  distillate,  con- 
sisting of  alcohol,  is  discarded,  and  the  distillation  is  stopped  when  the 
contents  of  the  retort  have  been  reduced  to  one-third  the  original  bulk. 
The  product  is  washed,  dried  by  contact  with  calcium  chloride,  and  rec- 
tified. 

Nitric  ether  is  a  colorless  liquid,  has  a  sweet  taste,  with  a  bitter 
after-taste  ;  sp.  gr.  1.112  at  17°;  boils  at  85°  —  86°;  burns  with  a  white 
flame.  Its  vapor,  when  heated,  explodes  violently  on  the  approach  of  a 
flame. 


ETHYLIC    ETHERS.  195 

Ethyl  nitrite — Nitrous  ether — ~  ^   I  O — was  obtained  by  Kunkel 

as  early  as  1681. 

Quite  a  number  of  processes  have  been  suggested  for  obtaining  this 
substance;  the  best  consists  of  directing  the  nitrous  fumes,  produced  by 
the  action  of  nitric  acid  upon  starch,  under  the  influence  of  heat,  into 
alcohol  contained  in  a  retort  connected  with  a  well-cooled  receiver. 

An  older  process,  still  frequently  used,  is  by  acting  upon  alcohol  di- 
rectly with  nitric  acid;  the  operation  must  be  conducted  in  a  capacious 
retort,  and  the  gentle  heat  applied  to  start  the  reaction  must  be  with- 
drawn as  soon  as  the  distillation  begins.  This  method  cannot  be  used  on 
a  large  scale,  owing  to  the  violence  of  the  action,  and  is  also  objection- 
able on  account  of  the  loss  of  alcohol  required  to  reduce  the  nitric  acid. 

Pure  ethylic  nitrate  is  a  yellowish  liquid;  has  a  peculiar,  apple-like 
odor,  and  a  sweetish,  sharp  taste;  sp.  gr.  0.947;  boils  at  18°.  Its  vapor- 
ization produces  a  great  diminution- of  temperature;  the  vapor  is  inflam- 
mable, burning  with  a  white  flame;  very  sparingly  soluble  in  water;  quite 
soluble  in  alcohol  and  ether. 

It  is  decomposed  by  warm  water  into  alcohol,  nitric  acid,  and  nitro- 
gen dioxide;  more  rapidly  by  alkalies,  with  formation  of  malate  and 
nitrate  of  the  alkaline  element,  but  without  formation  of  acetate.  It  is 
energetically  attacked  by  sulphuric  acid,  and  also  by  sulphydric  acid  and 
the  alkaline  sulphides.  Its  vapor,  when  passed  through  a  red-hot  tube, 
is  decomposed,  yielding  nitrogen,  nitrogen  dioxide,  carbon  monoxide,  hy- 
drocarbons, water,  ammonium  cyanide  and  carbonate,  an  oily  material, 
and  carbon.  W^hen  kept  it  is  liable  to  spontaneous  decomposition  into 
nitrogen  dioxide  and  malic  acid,  especially  in  the  presence  of  water. 

Its  vapor  rapidly  produces  anaesthesia;  it  is  not,  however,  used  in 
medicine  in  its  pure  form,  but  only  in  alcoholic  solution :  Spiritus  cetheris 
nitrosi(U.  S.,  Br.),  which  also  contains  aldehyde.  Owing  to  the  presence 
of  the  last-named  substance,  and  to  the  presence  of  water,  the  spirit  is 
very  liable  to  become  acid,  either  from  the  formation  of  acetic  acid  by  the 
oxidation  of  the  aldehyde,  or  from  the  decomposition  of  the  ether  under 
the  influence  of  water;  a  change  which  renders  it  unfit  for  use  in  many  of 
the  prescriptions  in  which  it  is  frequently  used,  especially  in  that  with  po- 
tassium iodide,  from  which  it  liberates  iodine.  The  presence  of  free  acid 
may  be  detected  by  effervescence  when  the  spirit  is  shaken  with  hydro- 
sodic  carbonate.  Its  acidity  may  be  corrected  by  shaking  with  potassium 
carbonate,  and  decanting,  provided  it  does  not  contain  water. 

Ethyl  "borates. — There  are  four  ethylic  borates,  three  of  which  cor- 
respond to  the  three  acids,  boric,  metaboric,  and  tetraboric.  The  borate, 
B03(C2H5)3,  is  a  colorless,  mobile  liquid,  having  a  peculiar,  agreeable  odor, 
and  a  bitter  taste;  soluble,  but  decomposed,  by  water;  soluble  in  alcohol 
and  ether;  burns  with  a  green  flame,  giving  off  dense  fumes  of  boric  acid. 

Ethyl  phosphates. — Four  of  these  compounds  are  known: 

PO4  (C^HJU., — Monethyl-phosphoric  acid — Phosphovinic  acid. 

PO4  (C2H5)2H— Diethyl-phosphoric  acid. 

PO4(CQH5)3 — Triethyl  phosphate — Phosphoric  ether. 

P2O7  (C2H5)4 — Tetrethylic  pyrophosphate — Pyrophosphoric  ether. 

Of  these,  the  first  two  possess  acid  properties  and  form  salts.  There 
exist  also  numerous  compounds  similar  in  constitution  to  the  ethyl  phos- 
phates, in  which  one  or  more  of  the  atoms  of  oxygen  are  replaced  by 


196  GENERAL    MEDICAL    CHEMISTRY. 

atoms  of  sulphur,  or  of  selenium,  e.  g.,  diethyl-sulphophosphoric  acid, 
PO3S  (C2H5)2H,  some  of  which  also  form,  salts. 

There  are  also  four  ethyl  phosphites,  two  of  which  are  acids  and  two 
neutral  ethers. 

Ethyl  sulphates.  —  These  are^two  in  number: 

SO4  (C2H5)  —  HEthyl-sulphuric,  or  sulphovinic  acid. 
SO4  (CaH6)2  —  Ethyl-sulphate  —  Sulphuric  ether. 

soj 

Ethyl-sulphuric  acid,  (C2HB)  v  O2  —  is  formed  as  an  intermediate  pro- 

H  ) 

duct  in  the  manufacture  of  ethylic  ether  (q.  v.).  It  is  prepared  by  slowly 
adding  sulphuric  acid  to  an  equal  volume  of  alcohol,  mixing  and  cooling1 
as  the  addition  progresses;  when  cold,  the  mixture  is  diluted  with  water, 
and  barium  carbonate  is  added  to  saturation;  the  clear  liquid,  on  concen- 
tration, yields  crystalline  plates  of  barium  ethyl-sulphate  [SO4  (C2H5)]2Ba", 
which,  when  exactly  decomposed  with  sulphuric  acid,  liberates  sulpho- 
vinic acid. 

Pure  ethyl-sulphuric  acid  is  a  colorless,  syrupy,  highly  acid  liquid;  sp. 
gr.  1.316;  soluble  in  water  and  alcohol  in  all  proportions;  insoluble  in  ether. 

It  decomposes  slowly  at  ordinary  temperatures,  more  rapidly  when 
heated.  When  heated  alone  or  with  alcohol,  it  yields  ether  and  sulphuric 
acid: 


When  heated  with  water,  it  yields  alcohol  and  sulphuric  acid: 


It  forms  crystalline  salts,  known  as  sulphov  incites,  one  of  which, 
sodium  sulphovinate,  SO4(C2HB)Na,  has  been  used  in  medicine.  It  is  a 
white,  deliquescent  solid,  either  crystalline  with  10.78  per  cent,  of  water 
of  crystallization,  or  granular  and  anhydrous;  the  former  fuses  at  86°,  the 
latter  does  not  fuse,  but  is  decomposed  at  100°;  it  is  soluble  in  0.61  parts 
of  water  at  17°.  Its  solution  should  give  no  precipitate  with  barium 
chloride. 

SO    ) 
Ethyl  sulphate,  /p  TT  \2  [  O2  —  the  true  sulphuric  ether,  is  obtained  by 

passing  vapor  of  sulphur  trioxide  into  pure  ethylic  ether,  thoroughly 
cooled;  the  product  is  purified  by  washing  with  water  and  milk  of  lime, 
and  concentrating  in  vacuo. 

It  is  a  colorless,  oily  liquid,  has  a  sharp,  burning  taste,  and  the  odor 
of  peppermint;  sp.  gr.  1.120;  it  cannot  be  distilled  without  decomposition; 
in  contact  with  water  it  is  decomposed  with  formation  of  sulphovinic  acid. 

By  the  action  of  an  excess  of  sulphuric  acid  upon  alcohol,  by  the  dry 
distillation  of  the  sulphovinates,  and  in  the  last  stages  of  manufacture  of 
ether,  a  yellowish,  oily  liquid,  having  a  penetrating  odor  and  a  sharp, 
bitter  taste,  is  formed;  this  is  sweet  or  heavy  oil  of  wine,  and  its  ethereal 


ETHYLIC   ETHEES.  197 

solution  is  Oleum  c&thereum  (U.  S.).  It  seems  to  be  a  mixture  of  ethyl-sul- 
phate with  hydrocarbons  of  the  series  CJd^.  On  contact  with  water  or 
an  alkaline  solution,  it  is  decomposed,  sulphovinic  acid  is  formed,  and  there 
separates  a  colorless  oil,  of  sp.  gr.  0.917,  boiling  at  280°,  which  is  light  oil 
of  wine.  This  oil  is  polymeric  with  ethylene,  and  is  probably  cetene, 
C16H32;  it  is  sometimes  called  etherine  or  etherol"  when  cooled  to  —  35°  it 
deposits  crystals,  which  fuse  at  110°  and  boil  at  260°. 

Ethyl  acetate—  Acetic  ether  —   2^  |^  i  O  —  is  obtained  by  distilling 

a  mixture  of  potassium  or  sodium  acetate,  sulphuric  acid,  and  alcohol;  the 
distillate  is  purified  by  washing  with  an  alkaline  solution  and  with  water, 
dried  by  contact  with  calcium  chloride,  and  rectified.  It  may  also  be  ob- 
tained by  passing  carbon  dioxide  through  an  alcoholic  solution  of  potas- 
sium acetate,  and  purifying  as  above. 

It  is  a  colorless  liquid;  has  an  agreeable,  ethereal  odor;  boils  at  74°;  sp. 
gr.  0.89  at  15°;  soluble  in  six  parts  water,  and  in  all  proportions  in  methyl 
and  ethyl  alcohols  and  in  ether;  a  good  solvent  of  essences,  resins,  can- 
tharidine,  morphjne,  gun-cotton,  and,  in  general,  of  substances  soluble  in 
ether;  burns  with  a  yellowish  white  flame. 

Chlorine  acts  energetically  upon  ethyl  acetate,  producing  products  of 
substitution,  varying  according  to  the  intensity  of  the  light  from  C4H6 
C1202  to  C4Cl8Oa. 

OTTO  ) 
Ethyl  formiate  —  Formic  ether  —  Q  JT   [•  O  —  is  obtained  by  decom- 

position of  a  formiate  by  a  process  similar  to  that  used  in  the  preparation 
of  the  acetate,  also  by  distilling  a  mixture  of  glycerin,  oxalic  acid,  and 
alcohol;  it  is  also  formed  in  the  manufacture  of  fulminating  mercury.  It 
is  obtained  as  a  commercial  product  by  distilling  a  mixture  of  starch, 
alcohol,  water,  sulphuric  acid,  and  manganese  dioxide. 

It  is  a  colorless  liquid;  has  an  odor  resembling  that  of  the  peach;  boils 
at  56°;  sp.  gr.  0.915  at  18°;  burns  with  bluish  flame;  soluble  in  nine  parts 
of  water,  and  in  all  proportions  in  alcohol  and  ether. 

It  is  isomeric  with  methyl  acetate: 


CSH,0,  C8H,0, 

Ethyl  formiate.  Methyl  acetate. 

The  different  arrangement  of  the  atoms  in  the  molecule  is  well  shown 
by  the  action  of  alkalies  upon  the  two  substances,  producing  ethylic  alco- 
hol and  a  formiate  in  one  case,  and  methylic  alcohol  and  an  acetate  in  the 
other. 


Ethyl  formiate.       Potassium  hydrate.        Potassium  formiate.  Ethyl  hydrate. 

C,H30  )  0  K  )  0  C,HS0  )   0  CH  ,  1  Q 

CH,\  (  H  f  l  K  f  '  H  f  ( 

Methyl  acetate.          Potassium  hydrate.        Potassium  acetate.  Methyl  hydrate. 

Ethyl  acetate  and  formiate  are  largely  used  in  combination  with  other 
compound  ethers  of  methyl,  ethyl,  and  amyl  in  the  manufacture  of  fruit- 


198 


GENERAL    MEDICAL    CHEMISTRY. 


essences,  which,  with  the  exception  of  essence  of  orange,  are  rarely,  if  ever, 
made  from  the  fruits  after  which  they  are  named.  In  the  following  table  is 
given  the  composition,  in  cubic  centimetres,  added  to  one  hundred  parts 
of  alcohol,  of  the  principal  artificial  essences  used  in  the  manufacture  of 
confectionery,  The  constituents  used  must  be  chemically  pure: 


ARTIFICIAL  FEUIT-ESSENCES. 


O 

Chloroform. 

Nitric  ether. 

d 

I 

formiate. 

j 

valerianate. 

1 

ceiianthylate. 

1 

pi  salic-ylate. 

I 

butyrate. 

valeriunate. 

Essence  of  orange. 

Co 
a 
li 

i  

1 

0 

i 

Oxalic  acid.  |  |-  8  g  | 

tun 
olio 

I   Of 

1 

Benzoic  acid,  j  ^  g  | 

1 

I 

| 

W 

1 

I 

I 

| 

I 

•z 

I 

! 

1 

Pineapple                   

a 

1 

1 

5 

10 

Melon 

2 

5 
5 
5 

1 
1 

1 

4 
5 
1 

5 

'i 

i 

'i 
i 

10 

10 

'i 

Strawberry         

9 

1 

1 

1 

3 
1 

2 
1 

Raspberry 

1 

1 
1 

0 

•• 

5 
B 

B 

'i 

Gooseberry  ....         

• 

Grape 

ID 
4 
10 
10 
5 

2 

1 
2 

'i 

1 

Apple     .             

1 

i 

2 

1 
5 

1 

10 

1 

Orange 

1 

1 

i 

•• 

•• 

1 

10 
10 

10 

1 

2 

1 

Pear      .... 

Lemon 

1 

2    10 
10 

10 

10 

"i 

1 

Wild  cherry  

5 
5 

2 

1 
4 
1 

Cherry 

8 

5 
5 

*5 

'i 
'5 

;! 

"fi 

5 

Plum  

B 

5 

'2 

•^ 

'i 

1 

Apricot  .     .     . 

4 

5 

i 

•• 

Peach  

•• 

B 

i 

2 

The  figures  indicate  the  number  of  cubic  centimetres  to  be  added  to  100  c.c.  of  alcohol. 

Other  mixtures  of  ethers  of  the  same  class  are  used  in  the  manufacture 
of  imitation  spirits.  Ethyl  formiate  predominates  in  essence  of  rum,  and 
ethyl  pelargonate  in  essence  of  cognac. 

CO 

Ethyl  carbonates  are  two  in  number:  C2H5  }•  O2,    ethyl-carbonic    or 


carbovinic  acid,  and 


CO 


O2,  ethyl  carbonate  or  carbonic  ether.     The 


former  is  a  monobasic  acid,  the  latter  a  neutral  body.  By  the  action  of 
ammonia  upon  ethyl  carbonate  in  the  cold  ethyl  carbonate  or  urethan, 
CO  (NHQ)O,C2H5,  is  formed;  and  under  the  influence  of  heat,  urea, 
CO(NHJ, 

Ethyl  oxalates.  —  Oxalic  acid,  being  dibasic,  forms  two  series  of 
ethers;  of  ethylic  ethers  there  are  C2O4  (C2H&-)H,  etTiyloxalic  or  oxalovinic 
acid,  and  C2O4  (C2H5),  ethyl  oxalate  or  oxalic  ether.  The  former  is  a  mono- 
basic acid,  isomeric  with  succinic  acid;  the  latter  is  neutral. 


Amylic. 
Amyl  nitrate,  p>f2  \  O — is  obtained  by  a  process  similar  to  that 

^6         11     ) 

used  for  preparing  the  corresponding  ethyl  compound,  by  the  distillation 
of  a  mixture  of  nitric  acid  and  amylic  alcohol  in  the  presence  of  a  small 
quantity  of  urea.  It  is  a  colorless,  oily  liquid;  has  an  odor  resembling 


AMYHC    ETHERS.  199 

that  of  bed-bugs,  and  a  sweetish,  burning  taste;  sp.  gr.  0.994  at  10°;  boils 
at  148°,  with  partial  decomposition. 

Amyl  nitrite — Amyl  nitrous  ether — ^  TT  [•  O — prepared  by  direct- 
ing the  nitrous  fumes,  evolved  by  the  action  of  nitric  acid  upon  starch, 
into  amyl  alcohol  contained  in  a  retort  heated  over  a  water-bath,  purifying 
the  distillate  by  washing  with  an  alkaline  solution,  and  rectifying. 

It  is  a  slightly  yellowish  liquid;  sp.  gr.  0.877;  boils  at  95°;  its  vapor 
explodes  when  heated  to  260°;  insoluble  in  water;  soluble  in  alcohol  in  all 
proportions;  vapor  orange-colored. 

Alcoholic  solution  of  potash  decomposes  it  slowly,  with  formation  of 
potassium  nitrite  and  oxides  of  ethyl  and  amyl.  When  dropped  upon 
fused  potash,  it  ignites  and  yields  potassium  valerianate. 

Amyl  nitrite  is  frequently  impure  ;  its  boiling-point  should  not  vary 
more  than  two  or  three  degrees  from  that  given  above. 

Amyl  sulphates — Are  the  same  in  constitution  as  those  of  ethyl, 
and  are  obtained  by  similar  methods.  Amyl  sulphuric  acid  is  of  historical 
interest,  as  it  was  by  its  formation  that  Williamson  showed  the  true  nature 
of  the  process  of  etherification.  The  amyl  sulphate  of  barium,  prepared 
from  active  amyl  alcohol,  is  three  times  more  soluble  than  that  made  from 
the  inactive — a  property  which  is  utilized  to  separate  the  two  alcohols. 

Amyl  acetate,    A  A     !•  O — Obtained  by  distilling  a  mixture  of  amyl 

alcohol,  potassium  acetate,  and  sulphuric  acid.  A  limpid,  colorless  liquid; 
sp.  gr.  0.8762  ;  boils  at  125°  ;  insoluble  in  water  ;  soluble  in  alcohol  and 
ether.  Its  alcoholic  solution  is  used  as  artificial  pear-essence. 

Of  the  great  number  of  other  ethers  of  this  series,  there  are  none  of 
particular  practical  importance  until  we  reach 

C^    TT    O  ) 
Cetyl   palmitate,     g  JV     I  O — Also  known  as  cetine,  which  is  the 

chief  constituent  of  Spermaceti— cetaceum  (U.  S.,  Br.).  This  is  the  con- 
crete portion,  obtained  by  expression  and  crystallization  from  alcohol,  of 
the  oil  contained  in  the  cranial  sinuses  of  the  sperm-whale.  It  forms 
white  crystalline  plates  ;  fusible  at  49°  ;  slightly  unctuous  to  the  touch  ; 
tasteless,  and  almost  odorless  ;  insoluble  in  water  ;  soluble  in  alcohol  and 
ether  ;  burns  with  a  bright  flame.  It  was  formerly  supposed  to  consist 
entirely  of  cetine,  but  recently  it  has  been  shown  to  contain  ethers  not 
only  of  palmitic,  but  also  of  stearic,  myristic,  and  laurostearic  acids  ;  and 
of  the  alcohols  :  lethal,  C12HS6O;  methal,  C14H30O;  ethal,  C16H34O;  and 
stethal,  C18H38O. 

OHO) 
Melissyl  palmitate — Melissin —   ft  |V    >•  O — Beeswax —  Ceraflava 

(U.  S.,  Br.) — consists  mainly  of  two  substances:  cerotic  acid,  which  is  solu- 
ble in  boiling  alcohol  and  melissyl  palmitate,  insoluble  in  that  liquid, 
united  with  minute  quantities  of  substances  which  communicate  to  the 
wax  its  color,  odor,  and  unctuousness.  Yellow  wax  melts  at  62° — 63°; 
after  bleaching,  which  is  brought  about  by  exposure  to  light,  air,  and  mois- 
ture, it  does  not  fuse  below  66°.  China  wax,  a  white  substance  resem- 
bling spermaceti,  is  a  vegetable  product  consisting  of  ceryl  cerotate, 
C,,HM0,  (CJHJ. 


200 


GENEKAL   MEDICAL   CHEMISTRY. 


ALDEHYDES. 

v  SERIES  CnHnaO. 


Formic  aldehyde CHaO. 

Acetic  aldehyde C2H4O. 

Propionic  aldehyde C3H6O. 

Butyric  aldehyde C4H8O. 

Isobutyric  aldehyde ;  C4H8O. 


Valerianic  aldehyde CBH10O. 

Caproic  aldehyde CeHi  A 

(Enanthylic  aldehyde C7H14O. 

Caprylic  aldehyde". C8H16O. 

Palmitic   aldehyde C16H8aO. 


Acetic  Aldehyde. 


Acetyl   hydride, 


TT 


O  ) 

^  j-  . 


Although  discovered  in  1821  by  Doebe- 


reiner,  and  subsequently  studied  by  Liebig,  it  is  only  of  late  years  that 
the  importance  of  this  body  in  the  organic  laboratory  has  been  recognized. 

It  is  formed  in  all  reactions  in  which  alcohol  is  deprived  of  hydrogen 
without  simultaneous  introduction  of  oxygen  ;  whence  the  name  of 
"  dehydrogenated  alcohol."  It  is  prepared  by  the  process  suggested  by 
Liebig:  a  mixture  of  sulphuric  acid,  six  parts;  water,  four  parts;  alcohol, 
four  parts,  powdered  manganese  dioxide,  six  parts,  is  placed  in  a  capacious 
retort,  which  is  connected  with  a  receiver  cooled  by  a  freezing  mixture  ; 
the  retort  is  warmed  very  slowly  and  gently.  The  distillate,  which  is  a 
mixture  of  water,  alcohol,  ether,  aldehyde,  and  other  substances,  is  re- 
distilled from  calcium  chloride  at  a  temperature  not  exceeding  50°.  This 
second  distillate  is  mixed  with  two  volumes  of  ether,  cooled  by  a  freezing 
mixture,  and  saturated  with  dry  ammonia  gas  ;  there  separate  fine, 
colorless  crystals  of  ammonium  acetylide,  having  the  composition  C2H3 
O,NH4,  which  are  washed  with  ether  and  dried  by  exposure  to  dry 
air  ;  they  are  placed  in  a  retort  over  the  water-bath  and  decomposed 
by  the  addition  of  the  proper  quantity  of  dilute  sulphuric  acid  ;  a  clear 
liquid  distils  over,  which  is  dried  by  contact  with  fused  calcium  chlo- 
ride, and  rectified  at  a  temperature  not  exceeding  35°. 

As  thus  obtained,  aldehyde  is  a  colorless,  mobile  liquid  ;  has  a  strong, 
suffocating  odor  ;  sp.  gr.  0.790  at  18°;  boils  at  21°;  soluble  in  all  pro- 
portions in  water,  alcohol,  and  ether.  K  perfectly  pure,  it  may  be  kept 
unchanged;  but  if  an  excess  of  acid  have  been  used  in  its  preparation,  it 
gradually  decomposes.  When  heated  to  100°,  it  is  decomposed  into 
water  and  crotonic  aldehyde. 

In  the  presence  of  nascent  hydrogen,  aldehyde  takes  up  H2  and 
regenerates  alcohol.  Chlorine  converts  it  into  acetyl  chloride,  C2H3O, 
Cl,  and  other  products.  Oxidizing  agents  quickly  convert  it  into  acetic 
acid,  C2H4O2.  Sulphuric,  hydrochloric,  and  sulphurous  acids  at  the 
ordinary  temperature  convert  it  into  a  solid  substance  called  paraldehyde, 
C6HiaO37  (?),  which  fuses  at  10.5°,  boils  at  124°,  and  is  more  soluble  in  cold 
than  in  warm  water.  When  heated  with  potassium  hydrate,  aldehyde 
becomes  brown,  a  brown  resin  separates,  and  the  solution  contains  potas- 
sium formiate  and  acetate.  Gaseous  ammonia  converts  aldehyde  into  the 
crystalline  ammonium  acetylide,  mentioned  above.  If  a  watery  solution 
of  aldehyde  be  treated,  first  with  ammonia  and  then  with  hydrogen  sul- 
phide, a  solid,  crystalline  base,  thialdme,  C6HlsNSa,  separates.  Aldehyde 


TKICHLOK  ALDEHYDE.  201 

also  forms  crystalline  compounds  with  the  alkaline  bisulphites.  It  de- 
composes solutions  of  silver  nitrate,  separating  the  silver  in  the  metallic 
form,  and  under  conditions  which  cause  it  to  adhere  strongly  to  glass; 
a  fact  which  is  utilized  in  making  certain  glass-silvering  solutions. 

Vapor  of  aldehyde,  when  inhaled  in  a  concentrated  form,  produces  as- 
phyxia, even  in  comparatively  small  quantity  ;  when  diluted  with  air  it 
is  said  to  act  as  an  anaesthetic.  When  taken  internally  it  causes  sudden 
and  deep  intoxication,  and  it  is  to  its  presence  that  the  first  products  of 
the  distillation  of  spirits  of  inferior  quality  owe  in  a  great  measure  their 
rapid,  deleterious  action. 


Trichloraldehyde, 

O  Ol  O  ) 
Trichloracetyl  hydride;  Chloral —   2     S*  f  — discovered  in   1832,  by 

Liebig.  It  is  one  of  the  final  products  of  the  action  of  chlorine  upon  al- 
cohol, and  is  obtained  by  passing  dry  chlorine  through  absolute  alcohol 
to  saturation  ;  applying  heat  toward  the  end  of  the  reaction,  which  re- 
quires several  hours  for  its  completion.  The  liquid  separates  into  two 
layers:  the  lower  is  removed  and  shaken  with  an  equal  volume  of  concen- 
trated sulphuric  acid  and  again  allowed  to  separate  into  two  layers;  the 
tipper  is  decanted;  again  mixed  with  sulphuric  acid,  from  which  it  is  dis- 
tilled; the  distillate  is  treated  with  quicklime,  from  which  it  is  again  dis- 
tilled, that  portion  which  passes  over  between  94°  and  99°  being  col- 
lected. It  sometimes  happens  that  chloral  in  contact  with  sulphuric  acid 
is  converted  into  a  modification,  insoluble  in  water,  known  as  metachloral; 
when  this  occurs  it  is  washed  with  water,  dried  and  heated  to  180°,  when 
it  is  converted  into  the  soluble  variety,  which  distils  over. 

Chloral  is  a  colorless  liquid,  unctuous  to  the  touch;  has  a  penetrating 
odor  and  an  acrid,  caustic  taste;  sp.  gr.  1.502  at  18°;  boils  at  94.4°;  very 
soluble  in  water,  alcohol,  and  ether;  dissolves  chlorine,  bromine,  iodine, 
sulphur,  and  phosphorus;  its  vapor  is  highly  irritating;  it  distils  without 
alteration. 

The  metachloral  mentioned  above  is  a  white,  volatile  solid,  having  an 
ethereal  odor;  insoluble  in  water,  alcohol,  and  ether;  convertible  at  180° 
into  the  liquid  chloral,  with  which  it  is  identical  in  chemical  properties. 

Although  chloral  has  not  been  obtained  by  the  direct  substitution  of 
chlorine  for  hydrogen  in  aldehyde,  its  reactions  show  it  to  be  an  aldehyde; 
it  forms  crystalline  compounds  with  the  bisulphites;  it  reduces  solutions 
of  silver  nitrate  in  the  presence  of  ammonia;  ammonia  and  hydrogen  sul- 
phide form  with  it  a  compound  similar  to  thialdine;  with  nascent  hydrogen 
it  regenerates  aldehyde;  oxidizing  agents  convert  it  into  trichloracetic 
acid. 

Alkaline  solutions  decompose  chloral  with  formation  of  chloroform 
and  a  formiate: 

C2HC13O     +     KHO     =     CHC13     +     CHOQK 

Chloral.  Potassium  Chloroform.  Potassium 

hydrate.  formiate. 

With  a  small  quantity  of  water,  chloral  forms  a  solid,  crystalline  hy- 
drate, heat  being  at  the  same  time  liberated.  This  hydrate  has  the  com- 


202  GENERAL    MEDICAL    CHEMISTRY. 

position  C2HC13O,H2O,  and  its   constitution,  as   well  as  that  of  chloral 
itself,  is  indicated  by  the  formulas: 

CH8  CC1,  CCI, 

CHO  '"  OHO  OH  (OH)a 

Aldehyde.  TrichloraMehyde  Chloral  hydrate, 

(chloral.) 

Chloral  hydrate  is  a  white,  crystalline  solid;  fuses  at  57°;  boils  at  98°, 
at  which  temperature  it  suffers  partial  decomposition  into  chloral  and 
water;  volatilizes  slowly  at  ordinary  temperatures;  is  very  soluble  in 
water;  neutral  in  reaction;  has  an  ethereal  odor,  and  a  sharp,  pungent 
taste.  Concentrated  sulphuric  acid  decomposes  it  with  formation  of 
chloral  and  chloralide.  Nitric  acid  converts  it  into  trichloracetic  acid. 
AVhen  pure  it  gives  no  precipitate  with  silver  nitrate  solution,  and  is  not 
browned  by  contact  with  concentrated  sulphuric  acid. 

Chloral  also  combines  with  alcohol,  with  elevation  of  temperature,  to 
form  a  solid,  crystalline  body — chloral  alcoholate. 

•       CC1--CH<8-C,H, 

Action  of  chloral  hydrate  uponthe  economy. — Although  it  was  the  ready 
decomposition  of  chloral  into  a  formiate  and  chloroform  which  first  sug- 
gested its  use  as  a  hypnotic  toLiebreich,  and  although  this  decomposition 
was  at  one  time  believed  to  occur  in  the  body  under  the  influence  of  the 
alkaline  reaction  of  the  blood,  more  recent  investigations  have  shown  that 
the  formation  of  chloroform  from  chloral  in  the  blood  is,  to  say  the  least, 
highly  improbable,  and  that  chloral  has,  in  common  with  many  other 
chlorinated  derivatives  of  this  series,  the  property  of  acting  directly  upon 
the  nerve-centres. 

Neither  the  urine  nor  the  expired  air  contain  chloroform  when  chloral 
is.  taken  internally;  when  taken  in  large  doses,  chloral  appears  in  the  urine. 
The  fact  that  the  action  of  chloral  is  prolonged  for  a  longer  period  than 
that  of  the  other  chlorinated  derivatives  of  the  fatty  series  is  probably 
due,  in  a  great  measure,  to  its  less  volatility  and  less  rapid  elimination. 

When  taken  in  overdose,  chloral  acts  as  a  poison,  and  its  use  as  such 
is  rapidly  increasing  as  acquaintance  with  its  powers  becomes  more  widely 
disseminated. 

No  chemical  antidote  is  known;  the  treatment  should  be  directed  to 
the  removal  of  any  chloral  remaining  in  the  stomach  by  the  stomach- 
pump,  and  to  the  maintenance  or  restoration  of  respiration. 

In  fatal  cases  of  poisoning  by  chloral  that  substance  may  be  detected 
in  the  blood,  urine,  and  contents  of  the  stomach  by  the  following  method: 
the  liquid  is  rendered  strongly  alkaline  with  potassium  hydrate;  placed 
in  a  flask,  which  is  warmed  to  50° — 60°,  and  through  which  a  slow  current 
of  air,  heated  to  the  same  temperature,  is  made  to  pass;  the  air,  after 
bubbling  through  the  liquid,  is  tested  for  chloroform  by  the  methods 
described  on  p.  165.  If  affirmative  results  are  obtained  in  this  testing,  it 
remains  to  determine  whether  the  chloroform  detected  existed  in  the 
fluid  tested  in  its  own  form,  or  resulted  from  the  decomposition  of  chloral; 
to  this  end  a  fresh  portion  of  the  suspected  liquid  is  rendered  acid  and 
tested  by  Hofmann's  method,  (p.  1G5);  if  chloroform  be  present,  the  char- 


KETOKES    OK    ACETONES.  203 

acteristic  odor  of  isobenzonitril  is  observed,  while  chloral,  not  being 
decomposed  in  acid  solution,  gives  a  negative  result.  The  nitrate  of  silver 
test  is  not  available  for  this  purpose  in  liquids  containing  chlorides,  as 
these,  in  the  presence  of  even  the  weakest  acids,  are  partially  decomposed 
with  liberation  of  hydrochloric  acid. 

The  corresponding  bromine  and  iodine  compounds  are  also  known. 

CBr3 
Bromal,    I        — a  colorless,  oily  liquid;  sp.  gr.   3.34;  boils  at  172°; 

CHO 

has  a  persistent,  sharp,  burning  taste,  and  a 'penetrating  odor;  its  vapor 
irritates  the  air-passages  and  eyes;  neutral;  soluble  in  water,  alcohol,  and 

CBr3 
ether.     By  union  with  water  it  forms  bromal  hydrate,    \  ;  large, 

CH(OH)9 

colorless,  transparent  crystals  ;  fusible  at  the  temperature  of  the  body; 
soluble  in  water;  has  the  same  taste  and  odor  as  bromal;  decomposed  by 
alkalies  into  bromoform  and  a  formiate.  Produces  anaesthesia  without 
sleep;  very  poisonous. 

lodal  and  its  hydrate  have  also  been  obtained. 

The  higher  aldehydes  of  this  series  are  obtainable  from  the  corre- 
sponding acids  by  distilling  a  mixture  of  calcium  formiate  and  the  calcium 
salt  of  the  corresponding  acid: 

(CH02)2Ca     +     (C4H702),Ca     =     2CO3Ca     +     2C4H8O 

Calcium  formiate.  Calcium  butyrate.  Calcium  carbonate.      Butyric  aldehyde. 

As  with  the  acids  and  alcohols,  there  exist  isomeres  of  the  aldehydes 
above  propylic  aldehyde;  such  are  butyral  and  valeraL  Caprylic  aldehyde, 
C8HlflO  is  one  of  the  products  of  decomposition  of  the  fatty  oils  at  high 
temperatures,  and,  together  with  acrolein  (q.  v.),  produces  the  unpleasant 
and  deleterious  odor  observed  in  engine-rooms,  especially  on  shipboard. 


KETONES  OR  ACETONES. 

SERIES  CnH2ttO. 

Dimethyl  Jcetone,  CO/  QTTS — Acetone — Acetyl  methylide — Pyroacetic 

ether — Pyroacetic  spirit — is  formed  as  one  of  the  products  of  the  dry  dis- 
tillation of  the  acetates;  by  the  decomposition  of  the  vapor  of  acetic  acid 
at  a  red  heat;  by  the  dry  distillation  of  sugar,  tartaric  acid,  etc.;  and  in 
a  number  of  other  reactions.  It  is  obtained  by  distilling  dry  calcium 
acetate  in  an  earthenware  retort  at  a  dull  red  heat;  the  distillate,  col- 
lected in  a  well-cooled  receiver,  is  freed  from  water  by  digestion  with 
fused  calcium  chloride,  and  rectified;  those  portions  being  collected  which 
pass  over  at  60°.  It  is  also  formed  in  large  quantity  in  the  preparation 
of  aniline,  when  that  substance  is  distilled  with  acetate  of  iron. 

It  is  a  limpid,  colorless  liquid;  sp.  gr.  0.7921  at  18°;  boils  at  56°; 
soluble  in  water,  alcohol,  and  ether,  has  a  peculiar,  ethereal  odor,  and  a 
burning  taste;  is  a  good  solvent  of  resins,  fats,  camphor,  gun-cotton; 
readily  inflammable. 


204  GENERAL   MEDICAL    CHEMISTRY. 

It  forms  crystalline  compounds  with  the  alkaline  bisulphites.  Chlorine 
and  bromine,  in  the  presence  of  alkalies,  convert  it  into  chloroform  or 
bromoform;  chlorine  alone  produces  with  acetone  a  number  of  chlorinated 
products  of  substitution.  Certain  oxidizing  agents  transform  it  into  a 
mixture  of  formic  and  acetiq  acids;  others  into  oxalic  acid. 

Acetone  has  been  found  to  exist"  in  the  blood  and  urine  in  certain 
pathological  conditions,  and  notably  in  diabetes;  the  peculiar  odor  ex- 
haled by  diabetics  is  produced  by  this  substance,  which  has  also  been 
considered  by  some  authors  as  being  the  cause  of  the  respiratory  derange- 
ments and  coma  which  frequently  occur  in  the  last  stages  of  the  disease. 

That  acetone  exists  in  the  blood  in  such  cases  is  certain;  it  is  not  cer- 
tain, however,  that  its  presence  produces  the  condition  designated  as 
acetoncemia.  It  can  hardly  be  doubted  that  the  acetone  thus  existing  in 
the  blood  is  indirectly  formed  from  diabetic  sugar,  and  it  is  probable  also 
that  a  complex  acid,  known  as  ethyldiacetic,  is  formed  as  an  intermediate 
product,  and  gives  rise  to  acetone  by  the  reaction: 


C6H903Na  +  2H20  =  C3H6O  +  C2H6O  +  CO3HNa 

Sodium  ethyl-         Water.        Acetone.         Alcohol.          Hydrosodio 
diacetate.  carbonate. 

The  higher  ketones  of  this  series,  propione,  butyrone,  etc.,  are  ob- 
tained by  similar  methods,  from  the  calcium  salts  of  the  corresponding 
acids.  Their  interest  is  purely  theoretical. 


MONAMINES. 

General  methods  of  preparation. — The  primary  monamines  are  formed 
by  the  action  of  potassium  hydrate  upon  the  corresponding  cyanic  ether: 

CNO,C2H5+2KHO=NH2,C2H5+CO3K2 

Ethyl  cyanate.         Potash.          Ethylamine.        Potassium 

carbonate. 

Or  by  heating  together  an  alcoholic  solution  of  ammonia  and  an  ether: 
C2H6I  +   NH3    =  HI   +   NH2,C2H5 

Ethyl  Ammonia.     Hydriodic          Ethylamine. 

iodide.  acid. 

Or  by  the  action  of  nascent  hydrogen  upon  the  cyanides  of  the  alcoholic 
radicals: 

CN,CH8    +    2H3    =    NH2,C2H6. 

Methyl  cyanide.        Hydrogen.  Ethylamine. 

The  secondary  monamines  are  formed  by  the  action  of  the  iodides  or 
bromides  of  the  alcoholic  radicals  upon  the  primary  monamines. 

The  tertiary  monamines  are  produced  by  the  distillation  of  the  hy- 
drates or  iodides  of  the  quaternary  ammoniums,  or  by  the  action  of  the 
iodides  of  the  alcoholic  radicals  upon  the  secondary  monamines 

General  properties. — The  amines  of  this  series,  containing  radicals  of 
monoatomic  alcohols,  have  the  same  power  of  saturation  as  ammonia. 


MOtf  AMIDES.  205 

They  are  volatile.  The  alkalinity  and  solubility  in  water  of  the  primary 
mbn  amines  are  greater  than  those  of  the  secondary,  and  those  of  the  sec- 
ondary greater  than  those  of  the  tertiary.  Their  chlorides  form  sparingly 
soluble  compounds  with  platinic  chloride,  similar  to  that  formed  with  the 
same  salt  by  ammonium  chloride.  Nitrous  acid  decomposes  the  mona- 
mines,  with  regeneration  of  the  corresponding  alcohol: 

NH2,C2H6  +  N02H  =  CJI5HO  +  H2O  +  Na. 

Ethylamine.  Nitrous  Ethylic  Water.        Nitrogen. 

acid.  alcohol. 

With  the  secondary  and  tertiary  monamines  the  same  reagent  produces 
nitroso-compounds,  in  which  an  atom  of  hydrog*en  is  replaced  by  the  group 
(NO)'. 

The  three  classes  of  monamines  may  be  separated  by  the  action  of  ethyl 
oxalate,  which  forms  with  the  primary  a  solid  compound,  and  with  the 
secondary  a  liquid,  while  the  tertiary  remains  free. 

There  are  but  few  of  the  monamines  of  this  series  which  are  of  practi- 
cal importance. 

OTT   ) 

Methylamine  —  MetJiylia  —   -g9  f-  N  —  is   obtained   by  decomposing 

methyl  cyanate  by  potash,  and  directing  the  vapors  through  dilute  hydro- 
chloric acid;  the  methyl  ammonium  chloride  thus  obtained  is  decomposed 
by  quicklime,  and  the  methylamine  collected  over  mercury. 

It  is  a  colorless  gas;  has  a  fishy,  ammoniacal  odor;  liquefies  a  few  de- 
grees below  0°;  inflammable;  is  the  most  soluble  gas  known;  one  volume 
of  water  dissolves  1,154  volumes  of  methylamine  at  12.5°,  and  959  volumes 
at  25°;  its  solution  is  strongly  alkaline  and  caustic,  and  has  the  odor  of  the 
gas.  Its  salts  are  soluble  in  boiling  alcohol.  In  solution  it  is  distinguish- 
able from  ammonia  and  from  ethylamine  by  its  failure  to  form  a  precipitate 
with  protochloride  of  molybdenum,  and  by  the  formation  of  a  reddish  pre- 
cipitate, insoluble  in  excess,  with  molybdenum  bichloride.  Its  chloro- 
platinate  is  yellow,  and  soluble  in  boiling  water. 


Dimethylamine—  Dimethylia—  N—  is  a  liquid  below  8°,  at 

which  temperature  it  boils;  has  an  ammoniacal  odor;  is  quite  soluble  in 
water;  is  formed  by  the  action  of  methyl  iodide  on  ammonia. 

Trimetjiylamine  —  Trimethylia—  (CH3)3N  —  is  formed  with  methyl- 
amine and  dimethylamine,  by  the  action  of  methyl  iodide  upon  ammonia, 
by  the  series  of  reactions; 

H3N  +  CHI  =  (CH3)H2N  +  HI. 
(CH3)H2N  +  CH3I  =  (CH3)2HN  +  HI. 
(CH3)aHN  +  CH3I  =  (CH3)3N  +  HI. 

It  is  also  formed  as  a  product  of  decomposition  of  many  organic  sub- 
stances, and  exists  widely  disseminated  in  nature.  It  is  one  of  the  pro- 
ducts of  the  action  of  potash  on  many  vegetable  substances,  alkaloids,  etc., 
of  the  putrefaction  of  fish  and  starch-paste;  it  occurs  in  cod-liver-oil,  in 
ergot,  in  chenopodium,  in  the  flowers  of  many  plants,  in  yeast,  in  guano, 
in  herring-pickle,  in  human  urine,  and  in  the  blood  of  the  calf.  It  is  usu- 
ually  obtained  by  distillation  from  the  pickle  in  which  fish  has  been  pre- 
served. 

At  temperatures  below  its  boiling-point,  9°,  it  is  an  oily  liquid,  having 


206  GENERAL    MEDICAL    CHEMISTKT. 

a  disagreeable  odor  of  spoiled  fish;  alkaline;  soluble  in  water,  alcohol,  and 
ether;  inflammable.  It  combines  with  acids  to  form  salts  of  trimethyl- 
ammonium,  which  are  crystallizable. 

It  has  frequently  been  mistaken  by  writers  upon  materia  medica  for 

/-/,VFT  \  ) 
its  isomere  propylamine,       *  jl    r  N,"  which  differs  from  it  in  odor  and  in 

boiling  at  50°.  Its  chloride,  under  the  names  chloride  of  propylamia,  of 
secalia,  ofsecalin,  has  been  used  in  the  treatment  of  gout  and  of  rheumatism. 

Tetramethyl  ammonium  hydrate  —  (CH3)4N,OH.  —  This  sub- 
stance, whose  constitution  is  similar  to  that  of  ammonium  hydrate,  is 
obtained  by  decomposing  the  corresponding  iodide,  (CH3)4NI,  formed  by 
the  action  of  methyl  iodide  upon  trimethylamine.  It  is  a  crystalline 
solid,  deliquescent,  very  soluble  in  water;  caustic;  not  volatile  without 
decomposition;  it  attracts  carbon  dioxide  from  the  air,  and  combines  with 
acids  to  form  crystallizable  salts. 

The  iodide  is  said  to  exert  an  action  upon  the  economy  similar  to  that 
of  curare. 

Ethylamine — Ethylia — '    a  T| '  [  N — is  obtained  by  the  action  of 

potash  upon  ethyl  cyanate.  It  is  a  light,  colorless,  mobile  liquid;  boils 
at  18.7°;  has  a  strong  odor  like  that  of  ammonia;  burns  with  a  bluish 
flame;  soluble  in  all  proportions  in  water,  alcohol,  and  ether.  It  expels 
ammonia  from  its  salts,  combining  itself  with  the  acid;  its  salts  are  for 
the  most  part  crystallizable,  and  are  soluble  in  absolute  alcohol.  With 
chlorine,  bromine,  and  iodine  it  forms  products  of  substitution  contain- 
ing two  atoms  of  the  halogen.  It  forms  precipitates  in  solutions  of  most 
of  the  metallic  salts,  and  behaves  like  ammonia  with  solutions  of  cupric 
salts.  The  precipitate  which  it  forms  in  solutions  of  the  alumina  salts  is 
soluble  in  an  excess  of  ethylamine. 

Diethylamine — Diethylia — '  s  4?  j-  N — is  an  inflammable,  color- 
less liquid,  very  soluble  in  water;  boiling  at  57°;  having  an  ammoniacal 
odor,  and  resembling  ethylamine  in  most  of  its  reactions. 

Triethylamine — Triethylia — (C2HB)SN — is  a  colorless  liquid,  lighter 
than  water,  in  which  it  is  sparingly  soluble;  boiling  at  91°;  having  an 
ammoniacal  odor  and  an  alkaline  reaction. 

Tetrethyl  ammonium  hydrate,  (C2H5)4N,OH — is  a  crystalline 
solid,  very  deliquescent;  soluble  in  water,  and  powerfully  basic. 

Choline ;  neurine,  ,Q  TT  OH  V  f  -^^H. — This  interesting  compound 

is  a  quaternary  monamtnonium  hydrate,  containing  three  methyl  groups, 
and  one  ethylene  hydroxide  group.  It  has  not  as  yet  been  found  to  exist 
free  in  the  animal  body,  but  only  as  a  constituent  of  those  important 
elements  of  nerve-tissue,  the  lecithins  (q.  v.).  It  was  first  obtained  from 
bile,  but  is  best  prepared  from  the  yolks  of  eggs. 

It  appears  as  a  thick  syrup,  soluble  in  water  and  in  alcohol,  and 
strongly  alkaline  in  reaction.  Even  in  dilute  aqueous  solution  it  prevents 
the  coagulation  of  albumin  and  redissolves  coagulated  albumin  and 
fibrin.  It  is  a  strong  base;  attracts  carbon  dioxide  from  the  air;  forms 
with  hydrochloric  acid  a  salt,  soluble  in  alcohol,  which  crystallizes  in 
plates  and  needles,  very  much  resembling  in  appearance  those  of  choles- 
terin. 

Choline  has  been  obtained  synthetically  by  the  action  of  a  concen- 


MONAMIDES.  207 

trated  solution  of  trimethylamine  upon  ethylene  oxide,  or  upon  ethylene 
chlorhydrate.    When  heated,  it  splits  up  into  glycol  and  trimethylamine. 

By  partial  oxidation  a  solid,  crystalline  base,  known  as  oxyneurine, 
oxycholine,  or  beta'in,  is  formed;  in  this  substance,  which  has  also  been 
obtained  by  synthesis,  the  group  C2H4OH  is  replaced  by  C2HaO,OH. 

Choline  is  isomeric  with  amanitine,  and  betai'n  with  muscarine  / 
poisonous  alkaloids  obtained  from  species  of  Agaricus. 

Besides  the  amines  here  considered,  many  containing  the  higher  alco- 
holic radicals  have  been  obtained.     There  are  also  amines  containing  two 
or   more  different   alcoholic   radicals,   such   as  methyl-ethyl-amylamine9 
CH, 
OH  5-N. 

ak, 


MONAMIDES. 

General  methods  of  preparation.  —  The  primary  monamides,  contain- 
ing radicals  of  the  acids  of  the  acetic  series,  are  formed: 
First.  —  By  the  action  of  heat  upon  an  ammoniacal  salt: 


Ammonium  acetate.          Water.  Acetamide. 

Second.  —  By  the  action  of  a  compound  ether  upon  ammonia: 


Ethyl  acetate.  Ammonia.  Acetamide.  Alcohol. 

Third.  —  By  the  action  of  the  chloride  of  an  acid  radical  upon  dry 
ammonia: 


Acetyl  chloride.  Ammonia.          Ammonium  Acetamide. 

chloride. 

The  secondary  monamides  of  the  same  class  are  obtained:  First,  by 
the  action  of  the  chlorides  of  acid  radicals  upon  the  primary  amides: 


Acetamide.  Acetyl  chloride.  Diacetamide.       Hydrochloric 

acid. 


Second. — By  the  action  of  hydrochloric  acid  upon  the  primary  mona- 
tnides  at  high  temperatures: 


Acetamide.  Hydrochloric       Diacetamide,  Ammonium 

acid.  chloride. 


208  GENERAL    MEDICAL    CHEMISTRY. 

The  tertiary  monamides  of  this  series  of  radicals  have  been  but  im- 
perfectly studied;  some  of  them  have  been  obtained  by  the  action  of 
the  chlorides  of  acid  radicals  upon  metallic  derivatives  of  the  secondary 
amides. 

General  properties. — The.  primary  monamides  containing  radicals  of 
the  fatty  acids  are  solid,  crystallizable,  neutral  in  reaction,  volatile  with- 
out decomposition,  mostly  soluble  in  alcohol  and  ether,  and  mostly  capa- 
ble of  uniting  with  acids  to  form  compounds  similar  in  constitution  to  the 
ammoniacal  salts.  They  are  capable  of  uniting  with  water  to  form  the 
ammoniacal  salt  of  the  corresponding  acid,  and  with  the  alkaline  hydrates 
to  form  the  metallic  salt  of  the  corresponding  acid,  and  ammonia.  The 
secondary  monamides,  containing  two  radicals  of  the  fatty  series,  are  acid 
in  reaction,  and  their  remaining  atom  of  extra-radical  hydrogen  may  be  re- 
placed by  an  electro-positive  atom. 

Formamide,  '       ,y  v  N — is  a  colorless  liquid;  soluble  in  water  and  in 

alcohol;  boils  at  192°;  formed  by  the  action  of  ethyl  formiate  upon  dry 
ammonia. 

(C*  TT  OY  ) 
Acetamide,  ^    2    3  W    [•  N  — is  obtained  by  heating,  under  pressure, 

a  mixture  of  ethyl  acetate  and  aqua  ammonite,  and  purifying  by  distilla- 
tion. It  is  a  solid,  crystalline  substance,  very  soluble  in  water,  alcohol, 
and  ether;  fuses  at  78°;  boils  at  221°;  has  a  sweetish,  cooling  taste,  and 
an  odor  of  mice.  Boiling  potassium  hydrate  solution  decomposes  it  into 
potassium  acetate  and  ammonia.  Phosphoric  anhydride  deprives  it  of  the 
elements  of  water,  and  forms  with  it  acetonitrile  or  methyl  cyanide. 

There  exist  also  amides  corresponding  to  tnonochlor  acetic  and  tri- 
chloracetic  acids. 


AMIDO-ACIDS  OF  THE  FATTY   SERIES. 

Amido-acetic  acid — Glycocol — Sugar  of  gelatin — Glycolamic  acid 
CH..NH. 

—  Glycine —  |  . — This  interesting  body  was  first  obtained  by  the 

COOH 

action  of  sulphuric  acid  upon  gelatin.  It  is  best  prepared  by  acting 
upon  glue  with  caustic  potassa,  ammonia  being  liberated;  sulphuric  acid 
is  then  added,  and  the  crystals  of  potassium  sulphate  separated;  the  liquid 
is  evaporated,  the  residue  dissolved  in  alcohol,  from  which  solution  the 
glycocol  is  allowed  to  crystallize. 

It  may  also  be  obtained  synthetically  by  a  method  which  indicates  its 
constitution — by  the  action  of  ammonia  upon  chloracetic  acid. 

CHa01  H\  CH8NHa 

|  +     H-N     =|  +     S 

COOH  H/  COOH 

Chloracetic  Ammonia.  Amidoacetic          Hydrochloric 

acid.  acid.  acid. 

It  may  be  obtained  from  ox-bile,  in  which  it  exists  as  the  salt  of  a  con- 
jugate acid;  from  uric  acid  by  the  action  of  hydriodic  acid;  and  by  the 
union  of  formic  aldehyde,  hydrocyanic  acid,  and  water.  It  is  isomeric 
with  glycolamide. 


AMIDOACIDS    OF    THE    FATTY    SERIES.  209 

It  has  been  found  to  exist  free  in  animal  nature  only  in  the  muscle  of 
the  scallop,  and,  when  taken  internally,  its  constituents  are  eliminated  as 
urea.  In  combination  it  exists  in  the  gelatinoids,  and  with  cholic  acid 
as  sodium  glycocholate  (q.  v.)  in  the  bile;  it  is  one  of  the  products  of  de- 
composition of  glycocholic  acid,  hyoglycocholic  acid,  and  hippuric  acid  by 
dilute  acids  and  by  alkalies,  and  of  the  decomposition  of  tissues  contain- 
ing gelatinoids. 

It  appears  as  large,  colorless,  transparent  crystals;  has  a  sweet  taste; 
melts  at  170°;  decomposes  at  higher  temperatures;  sparingly  soluble  in 
cold  water;  much  more  soluble  in  warm  water;  insoluble  in  absolute 
alcohol  and  in  ether;  acid  in  reaction. 

It  combines  with  acids  to  form  crystalline  compounds,  which  are  de- 
composed at  the  temperature  of  boiling  water;  hot  sulphuric  acid  car- 
bonizes it;  nitric  acid  converts  it  into  glycolic  acid  (q.  v.)',  with  hydro- 
chloric acid  it  forms  a  chloride;  heated  under  pressure  with  benzoic  acid 
it  forms  hippuric  acid.  Its  acid  function  is  more  marked;  it  expels  car- 
bonic and  acetic  acids  from  calcium  carbonate  and  plumbic  acetate.  The 
presence  of  a  small  quantity  of  glycocol  prevents  the  precipitation  of 
cupric  hydrate  from  cupric  sulphate  solution  by  potassium  hydrate;  the 
solution  becomes  dark  blue,  does  not  yield  cuprous  hydrate  on  boiling, 
and  precipitates  crystalline  needles  of  copper  glycolamate  on  the  addition 
of  alcohol  to  the  cold  solution.  With  ferric  chloride  it  gives  an  intense 
red  solution,  whose  color  is  discharged  by  acids,  and  reappears  on  neu- 
tralization. With  phenol  and  sodium  hypochlorite  it  gives  a  blue  color, 
as  does  ammonia.  By  oxidation  with  potassium  permanganate  in  alka- 
line solution  it  yields  carbon  dioxide,  oxalic,  carbonic,  and  oxamic  acids, 
and  water.  It  also  forms  crystalline  compounds,  with  many  salts  and 
ethers.  Methyl  glycolamate  is  isorneric  with  sarcosine: 

CH2NH2  CH2NH2  CH2NH(CH3) 

COOH  COOCH3  COOH 

Glycocol  Methyl-  Sarcosine 

(amido-acetic  acid).  glycolamate.  (methyl-glycocol). 

CH,[NH(CH3)] 

Methyl-glycocol — Sarcosine  \  — This  substance,  which 

COOH 

is  isomeric  with  alanine  and  with  lactamide  (q.  y.),  does  not  exist  as  such 
in  animal  nature,  but  has  been  obtained  from  creatine  (q.  v.)  by  the  action 
of  barium  hydrate: 

C4H9N302     +     H,0     =     03H7N02     +     CON2H4 

Creatine.  Water.  Sarcosine.  Urea. 

Urea  being  formed  at  the  same  time,  and  decomposed  by  the  further  ac- 
tion of  the  barium  hydrate  into  ammonia  and  barium  carbonate. 

Its  constitution  is  indicated  by  its  synthetic  formation  from  chlor- 
acetic  acid  and  methylamine: 

CH.C1  CH,\  CH2[NH(CH3)] 

|  +         H— N  '  =      |  +     * 

COOH  H/  COOH 

Chloracetic  Melliylamine.  Sarcosine.  Hydrochloric 

acid.  acid. 

14 


210  GENERAL    MEDICAL    CHEMISTRY. 

It  crystallizes  in  colorless,  transparent  prisms;  very  soluble  in  water; 
sparingly  soluble  in  alcohol  and  ether.  Its  aqueous  solution  is  not  acid, 
and  has  a  sweetish  taste;  it  unites  with  acids  to  form  crystalline  salts, 
but  does  not  form  metallic  salts.  It  is  capable  of  combining  with  cyan- 
amide  to  form  creatine. 


Biliary  Acids. 

The  bile  of  most  animals  contains  the  sodium  salts  of  two  amido-acids 
of  complex  constitution.  These  acids  may  be  decomposed  into  a  non- 
nitrogenized  acid  (cholic  acid),  and  either  an  amido-acid  (glycocol),  or  an 
amido-sulphurous  acid  (taurine).  The  following  biliary  acids  have  been 
described : 

Glycocholic  acid,  C26H43NO6 — (sometimes  designated  as  Acide  cho- 
lique,  Cholsciure,  Cholic  acid,  especially  by  French  and  German  writers, 
who  retain  the  names  given  it  by  Gmelin,  but  which  had  been  previously 
applied  to  another  substance  by  Demaryay.)  It  exists  as  its  sodium  salt 
in  the  bile  of  the  herbivora,  and  in  much  smaller  proportion  in  that  of  the 
carnivora;  it  exists  in  small  quantity  in  human  blood  arid  urine  in  icterus; 
in  human  bile  its  quantity  varies  with  the  diet. 

It  is  best  obtained  from  ox-bile;  this  is  evaporated  to  one-fourth  of 
its  original  volume,  the  residue  is  ground  up  with  animal  charcoal,  and 
dried  at  100°;  the  dry  mass,  while  still  hot,  is  broken  up  and  introduced 
into  a  flask,  in  which  it  is  digested  with  absolute  alcohol,  with  repeated 
agitation  for  some  days;  the  colorless,  filtered  alcoholic  solution  is  par- 
tially evaporated,  but  not  to  the  extent  of  becoming  syrupy,  then  mixed 
•with  an  excess  of  anhydrous  ether,  which,  if  the  reagents  were  free  from 
water,  causes  the  immediate  separation  of  a  crystalline  precipitate  of  the 
mixed  biliary  salts.  If  the  alcohol  or  ether  used  contain  water,  the  pre- 
cipitate is  at  first  resinous  and  only  becomes  crystalline  after  standing,  or 
does  not  become  crystalline  if  the  proportion  of  water  be  too  great.  The 
crystalline  deposit  is  collected  upon  a  filter,  washed  with  ether  and  dis- 
solved in  a  small  quantity  of  water  ;  to  the  aqueous  solution  a  small 
quantity  of  ether  is  added,  and  then  enough  dilute  sulphuric  acid  to  ren- 
der the  mixture  permanently  cloudy;  the  glycocholic  acid  gradually  crys- 
tallizes out,  and  may  be  further  purified  by  solution  in  alcohol,  and 
precipitation  with  a  great  excess  of  ether. 

Glycocholic  acid  forms  brilliant,  colorless,  transparent  needles,  which 
are  sparingly  soluble  in  cold  water,  readily  soluble  in  warm  water  and  in 
alcohol,  almost  insoluble  in  ether.  The  watery  solution  is  acid  in  reac- 
tion, and  tastes  at  first  sweet,  afterward  intensely  bitter;  its  alcoholic  solu- 
tion exerts  a  right-handed  polarization  [«]D  =  +29°;  when  evaporated 
it  leaves  the  acid  in  a  resinous  form. 

When  heated  with  potash,  baryta,  or  dilute  sulphuric  or  hydrochloric 
acid,  it  is  decomposed  into  cholic  acid  and  glycocol: 

C,,H.3N06     +     H,0     =     C=1H400S     +     CaH8N02. 

Glycocholic  acid.  Water.  Cholic  acid.  Glycocol. 

Glycocholic  acid  dissolves  unchanged  in  cold  concentrated  sulphuric 
acid,  and  is  precipitated  on  dilution  of  the  solution  with  water;  if  the 
mixture  be  warmed  the  bile  acid  is  decomposed,  and  there  separate  oily 


BILIARY    ACIDS.  211 

drops  of  cholotiic  acid,  CaoH41NOB,  an  r.cid  substance,  differing  from  gly- 
cocholic  acid  by  —  H2O.  When  allowed  to  remain  long  in  contact  with 
concentrated  sulphuric  acid,  glycocholic  acid  is  converted  into  a  colorless, 
resinous  mass,  which  slowly  forms  a  saffron-yellow  solution  with  the 
mineral  acid,  which  turns  flame-red  when  warmed,  and  which,  on  dilution, 
deposits  a  flocculeiit  material  which  is  colorless,  greenish,  or  brownish, 
according  to  the  temperature  at  which  it  is  formed.  Glycocholic  acid, 
altered  by  contact  with  concentrated  sulphuric  acid,  absorbs  oxygen  when 
exposed  to  the  air,  and  turns  red,  then  blue,  and  finally  brown  after  a  few 
days. 

Of  the  salts  of  glycocholic  acid,  sodium  glycocholate,  C26H42NOcNa, 
exists  in  the  bile;  it  crystallizes  in  stellate  needles,  very  soluble  in  water, 
less  so  in  absolute  alcohol,  and  insoluble  in  ether;  its  alcoholic  solution 
exerts  right-handed  polarization  [«]D= +25.7°. 

Lead  glycocholate,  (C26H42NOc)2Pb  (?) — is  formed  as  a  white,  floccu- 
lent precipitate,  when  solution  of  lead  subacetate  is  added  to  a  solution 
of  a  glycocholate  or  of  glycocholic  acid;  with  the  neutral  acetate  the  pre- 
cipitation does  not  occur  in  the  presence  of  an  excess  of  acetic  acid.  It 
is  soluble  in  alcohol,  and  in  an  excess  of  lead  acetate  solution. 

The  glycocholates  of  the  alkaline  earths  are  soluble  in  water.  Gly- 
cocholic acid  and  the  glycocholates  react  with  Pettenkofer's  test  (see 
below). 

Glycocholic  acid  forms  compounds  with  the  alkaloids,  some  of  which 
are  crystalline,  others  amorphous;  they  are  for  the  most  part  very  sparingly 
soluble  in  water,  but  readily  soluble  in  solutions  of  the  biliary  salts  and 
in  bile. 

Taurocholic  acid,  C?6H4BNO7S  (called  by  Streckei1  choleic  acid), 
exists  as  its  sodium  salt  in  the  bile  of  man  and  of  the  carnivora,  and  in 
much  less  abundance  in  that  of  the  herbivora ;  in  the  bile  of  the  dog  it 
seems  to  be  unaccompanied  by  any  other  biliary  acid.  It  may  be  obtained 
from  dog's  bile  by  a  modification  of  the  method  described  under  glyco- 
cholic acid;  the  watery  solution  is  riot  treated  with  sulphuric  acid,  as  in 
the  preparation  of  that  acid,  but  with  solution  of  basic  lead  acetate  and 
ammonia.  The  precipitate  so  formed  is  extracted  with  boiling  alcohol, 
the  solution  filtered  hot  and  treated  with  hydrogen  sulphide  ;  the  clear 
liquid,  filtered  from  the  precipitated  lead  sulphide,  is  evaporated  to  a  small 
bulk  and  treated  with  a  large  excess  of  ether;  the  acid  is  precipitated  in 
the  resinous  form,  but,  after  standing  for  a  varying  period,  assumes  the 
crystalline  form. 

When  carefully  prepared  it  forms  silky,  crystalline  needles,  which, 
when  exposed  to  the  air,  deliquesce  rapidly,  and  which,  even  under  abso- 
lute ether,  are  gradually  converted  into  a  transparent,  amorphous,  resinous 
mass.  It  is  soluble  in  water  and  in  alcohol,  insoluble  in  ether;  its  aqueous 
solution  is  very  bitter;  in  alcholic  solution  it  deviates  the  plane  of  polar- 
ization to  the  right,  [a]  D=24.5°;  its  solutions  are  acid  in  reaction. 

Taurocholic  acid  is  very  readily  decomposed  by  heating  with  barium 
hydrate,  with  dilute  acids,  and  even  by  evaporation  of  its  solution,  into 
cholic  acid  and  taurine. 

C,6HisNO,S     +     H20     =     C!4H400S     +     C2H,NO5S 

Taurocholic  acid.  Water.  Cholic  acid.  Taurine. 

The  same  decomposition  occurs  in  the  presence  of  putrefying  material 
and  in  the  intestine.  Taurocholic  acid  has  not  been  found  to  accompany 
glycocholic  in  the  urine  of  icteric  patients. 


212  GENERAL   MEDICAL    CHEMISTRY. 

The  taurocholates  are  neutral  in  reaction;  those  of  the  alkaline  metals 
are  soluble  in  alcohol  and  in  water;  and  by  long"  contact  with  ether  they 
assume  the  crystalline  form.  They  may  be  separated  from  the  glycocho- 
lates  in  watery  solution,  either:  1st,  by  dilute  sulphuric  acid  in  the 
presence  of  a  small  quantity  of  etherjfcvhich  precipitates  glycocholic  acid 
alone;  or  2d,  by  adding  neutral  load  acetate  to  the  solution  of  the  mixed 
salts,  which  must  be  neutral  in  reaction,  lead  glycocholate  is  precipitated 
and  separated  by  filtration;  to  the  mother  liquor  basic  lead  acetate  and 
ammonia  are  added,  when  lead  taurocholate  is  precipitated.  The  acids 
are  obtained  from  the  hot  alcoholic  solutions  of  the  lead  salts  by  decompo- 
sition with  hydrogen  sulphide,  filtration,  concentration,  and  precipitation 
by  ether. 

Solutions  of  the  taurocholates,  like  those  of  the  glycocholates,  have 
the  power  of  dissolving  cholesterin  and  of  emulsifying  the  fats;  they 
also  form  with  the  salts  of  the  alkaloids  compounds  which  are  insoluble 
in  water,  but  soluble  in  an  excess  of  the  biliary  salt.  The  taurocholate  of 
morphine  is  crystallizable.  They  react  with  Pettenkofer's  test. 

ffyoglycocholic  acid,  C27H43NO6  and  hyotaurocholic  acid,  C27H45NO6 
S  (?)  are  conjugate  acids  of  hyocholic  acid,  C2&H40O4,  and  glycocol  and 
taurine,  which  exist  in  the  bile  of  the  pig.  ChenctaurocJiolw  acid,  a 
conjugate  acid  of  taurine  and  chenocholic  acid,  C27H44O4,  is  obtained  from 
the  bile  of  the  goose. 

Cholic  acid,  C24H40O5  (called  by  Strecker,  cholalic  acid),  is  a  product 
of  decomposition  of  glyco-  and  taurocholic  acids,  obtained  as  indicated 
above.  It  also  occurs,  as  the  result  of  a  similar  decomposition,  in  the 
intestines  and  faeces  of  both  herbivora  and  carnivora.  It  forms  large, 
clear,  deliquescent  crystals;  sparingly  soluble  in  water,  readily  soluble  in 
alcohol  and  ether;  intensely  bitter  in  taste,  with  a  sweetish  aftertaste; 
in  alcoholic  solution  it  is  dextrogyric  [«]„  —  35°.  The  alkaline  cholates  are 
crystallizable  and  readily  soluble  in  water,  the  others  difficultly  soluble. 
Cholic  acid  and  the  cholates  respond  to  Pettenkofer's  test. 

By  boiling  with  acids  or  by  continued  heating  to  200°,  cholic  acid 
loses  the  elements  of  water,  and  is  transformed  into  dyslysin,  C24H36O3,  a 
neutral,  resinous  material,  insoluble  in  water  and  alcohol,  sparingly  solu- 
ble in  ether. 

Tests  for  the  biliary  acids — The  Pettenkofer  reaction. — All  of  the 
biliary  acids,  and  the  cholic  acid  and  dyslysin  obtained  by  their  decom- 
position, have  the  property  of  forming  a  yellow  solution  with  concen- 
trated sulphuric  acid,  the  color  of  which  rapidly  increases  in  intensity, 
and  which  exhibits  a  green  fluorescence.  Their  watery  solutions  also, 
when  treated  with  a  small  quantity  of  cane-sugar  and  with  concentrated 
sulphuric  acid,  so  added  that  the  mixture  acquires  a  temperature  of  70° 
but  does  not  become  heated  much  beyond  that  point,  develop  a  beauti- 
ful cherry-red  color,  which  gradually  changes  to  dark  reddish  purple. 
Although  this  reaction  is  observed  in  the  presence  of  very  small  quanti- 
ties of  the  biliary  acids,  it  loses  its  value,  unless  applied  as  directed  below, 
from  the  fact  that  many  other  substances  give  the  same  reaction,  either 
with  sulphuric  acid  alone,  or  in  the  presence  of  cane-s*ugar.  Among  these 
substances  are  many  which  exist  naturally  in  animal  fluids,  or  which  may 
be  introduced  with  the  food  or  as  medicines;  such  are  cholesterin,  the 
albuminoids,  lecithin,  oleic  acid,  cerebrin,  phenol,  turpentine,  tannic  acid, 
salicylic  acid,  morphine,  codeine,  many  oils  and  fats,  cod-liver  oil,  etc.  It 
has  been  suggested  that  a  distinction  could  be  made  between  the  color 
produced  by  the  Pettenkofer  test  with  the  biliary  acids,  and  those  pro- 


BILIARY    ACIDS.  213 

cluced  by  the  same  test  with  other  substances,  by  spectroscopic  observa- 
tion; the  test  with  biliary  acids  in  watery  solution  exhibiting  a  single 
dark  and  broad  absorption-band,  extending  from  E  to  midway  between 
D  and  E;  the  same  test  with  the  acids  in  alcoholic  solution  shows  two 
bands,  one  similar  to  that  already  described,  and  a  second  narrower  and 
fainter  at  F.  But  while  this  spectrum  differs  from  those  observed  in  the 
purple  solutions  obtained  with  many  other  bodies  under  similar  con- 
ditions, it  does  not  differ  sufficiently  from  that  obtained  with  the  mor- 
phine salts  and  with  other  substances,  to  render  it  a  safe  method  for  con- 
trolling the  test. 

The  following  method  of  applying  Pettenkofer's  test  to  the  urine  and 
other  fluids  removes,  we  believe,  every  source  of  error.  The  urine,  etc., 
is  first  evaporated  to  dryness  at  the  temperature  of  tlie  water-bath,  a 
small  quantity  of  coarse  animal  charcoal  having  been  added;  the  residue 
is  extracted  with  absolute  alcohol,  the  alcoholic  liquid  filtered,  partially 
evaporated,  and  treated  with  ten  times  its  bulk  of  absolute  ether;  after 
standing  an  hour  or  two,  any  precipitate  which  may  have  formed  is  col- 
lected upon  a  small  filter,  washed  with  ether,  and  dissolved  in  a  small 
quantity  of  water;  this  aqueous  solution  is  placed  in  a  test-tube,  a  drop 
or  two  of  a  strong  aqueous  solution  of  cane-sugar  (sugar,  1;  water,  4),  and 
then  pure  concentrated  sulphuric  acid,  are  added;  the  addition  of  the  acid 
being  so  regulated,  and  the  test-tube  dipped  from  time  to  time  in  cold 
water,  that  the  temperature  shall  be  from  60° — 75°.  In  the  presence  of 
biliary  acids  the  mixture  usually  becomes  turbid  at  first,  and  then  turns 
cherry-red  and  finally  purple,  the  intensity  of  the  color  varying  with  the 
amount  of  biliary  acid  present. 

Physiological  chemistry  of  the  biliary  acids. — That  these  substances 
do  not  normally  pre-exist  in  the  blood,  and  are  consequently  formed  in 
the  liver,  and  that  they  are  not  reabsorbed  from  the  intestine  unchanged, 
is  shown  by  the  experiments  of  Kunde,  Moleschott,  and  Feltz  and  Ritter. 
The  last-named  have  found  that  solutions  of  the  biliary  salts,  injected 
into  the  circulation  in  small  quantity,  cause  a  diminution  in  the  frequency 
of  the  pulse  and  of  the  respiratory  movements,  a  lowering  of  the  tempera- 
ture and  arterial  tension,  and  disintegration  of  the  blood-corpuscles;  in 
large  doses  (2 — 4  grams  for  a  dog)  they  produce  the  same  effects  to  a  more 
marked  degree;  epileptiform  convulsions,  black  and  bloody  urine,  and 
death,  more  or  less  rapidly.  These  effects  do  not  follow  the  injection  of 
the  products  of  decomposition  of  the  biliary  acids,  except  cholic  acid,  arid 
in  that  case  the  symptoms  are  much  less  well  marked.  Nor  are  the  bil- 
iary acids  discharged  unaltered  with  the  faeces;  they  are  decomposed  in 
the  intestine.  The  extract,  suitably  purified,  of  the  contents  of  the  upper 
part  of  the  small  intestine,  gives  a  well-marked  reaction  with  Petten- 
kofer's test;  while  a  similar  extract  of  the  contents  of  the  lower  part  of 
the  large  intestine,  or  of  the  fasces,  fail  to  give  the  reaction,  and  conse- 
quently are  free  from  glyco-  or  taurocholic,  cholic. acid,  or  dyslysin;  the 
faeces  have,  moreover,  not  been  found  to  contain  either  taurine  or  glyco- 
col.  During  the  processes,  at  present  but  imperfectly  understood,  which 
take  place  in  the  intestine,  the  bile-acids  are  undoubtedly  decomposed 
into  cholic  acid  and  taurine  or  glycocol,  which  are  subsequently  reab- 
sorbed, either  as  such,  or  after  having  been  subjected  to  further  decom- 
position; and  as  a  consequence  of  their  decomposition  they  probably 
have  some  influence  upon  intestinal  digestion. 

The  biliary  salts  are  precipitated  from  their  aqueous  solution,  or  from 
bile,  by  fresh  gastric  juice  from  the  same  animal;  but  they  are  riot  so 


214 


GENERAL    MEDICAL    CHEMISTRY. 


precipitated  if  the  gastric  juice  contain  peptones.  The  proportion  of  bil- 
iary salts  in  human  bile  seems  to  vary  considerably,  as  shown  by  the  fol- 
lowing analyses: 


Mucin  

I. 

n. 

in. 

jr. 

Y_ 

VI. 

VII. 

VIII. 

V.57 
4.90 
1.46 

IX. 

1.29 
0.35 
0.73 
0.87 
3.03 
1.39 

2.66 
0.16 
0.32 

7.22 

2.98 
0.26) 
0.92  f 

9.14 

2.21 
4.73 

10.79 

1.45 
3.09 

5.65 

(  6.  25* 
10.04 

j 

I  4.48 
0.64 
3.86 

2.48 
0.25 
0.05 
0.75 
2.09 
0.82 
0.46? 
90.88 
9.12 

1.29 
0.34 
0.36 
1.93 
0.44 
1.63 
1.46? 
91.08 
8.92 

C'holeaterin 

Fats.              

Taurocholate  of  sodium,   J 
Glycocholate  of  sodium,     )"  '  ' 
Soaps  

0.65 
86.00 
14.00 

0.77 
85.92 
14.08 

1.08 
82.27 
17.73 

0.63 

89.81 
10.19 

Water  

Total  solids 

I.  Frerichs:  Bile  from  man,  set.  18,  killed  by  a  fall.  II.  Frericha  :  Male,  aet.  22,  died 
of  a  wound.  III.  Gorup-Besanea :  Male,  aet.  49,  decapitated.  IV.  Gorup-Besanez  : 
Female,  set.  29, decapitated.  V.  Jacobsen  :  Male,  biliary  fistula.  VI.,  VII.  Trifanow- 
ski:  Males.  VIII.  Socoloff  :  Mean  of  six  analyses  of  human  bile.  IX.  Hoppe-Seyler  : 
Mean  of  five  analyses  of  bile  from  subjects  with  healthy  livers. 

Pathologically,  the  biliary  acids  may  be  detected  in  the  blood  and 
urine  in  icterus  and  acute  atrophy  of  the  liver,  although  by  no  means  as 
frequently  as  the  biliary  coloring  matters. 

CH-CH2(NH2) 
Amidopropionic  Acid — Alanine,  I  . — Isomeric  with 

COOH 

sarcosine  and  with  lactamide;  does  not  exist,  so  far  as  is  known  at  present, 
in  nature.  It  is  obtained  by  the  action  of  alcoholic  ammonia  upon  bromo- 
proprionic  acid: 

CH2Br  CH2(NH2) 

1  /H\    \       I 

CH       +  2/H— N)=CH2  +BrNII4. 

I          VH/  /    i 

COOH  COOH 


Bromopropi-         Ammonia.  Amidopropi-        Ammonium 

onic  acid.  onic  acid.  bromide. 

It  may  also  be  prepared  by  starting  from  lactic  acid,  from  which  it  differs 
by  containing  NH2  in  place  of  OH. 

It  crystallizes  in  large,  oblique,  rhombic  prisms;  very  soluble  in  water; 
sparingly  soluble  in  alcohol;  insoluble  in  ether.  Its  aqueous  solution  is 
neutral  and  sweet.  Nitrous  acid  converts  it  into  lactic  acid,  nitrogen,  and 
water.  It  dissolves  in  acids  without  neutralizing  them,  but  yet,  in  cer- 
tain cases,  with  the  formation  of  crystalline  compounds.  Its  barium,  lead, 
copper,  and  silver  salts  are  soluble  and  crystalline. 

Amidobutyric  Acid — JButalanine,  C4H9NO2,  and  Amidovaleri- 
anic  acid,  CBHnNOa — are  only  of  theoretic  interest  at  present.  The 
latter  has  been  found  in  the  tissue  of  the  pancreas  and  among  the  pro- 
ducts of  the  action  of  pancreatic  juice  upon  albumin.  They  are  both 
among  the  products  of  the  decomposition  of  albumin  by  caustic  baryta. 

CH.— C3H— CHa(NH2) 

Amidocaproic    Acid — Leucine —  |  =C6II13NO3 

COOH 
— was  first  obtained  by  Proust  as  a  product  of  putrefaction  of  gluten  in 


LEUCINE.  215 

presence  of  water.  It  has  since  been  found  to  exist  widely  distributed  in 
animal  nature;  it  has  been  obtained  from  the  normal  spleen,  pancreas,  sali- 
vary, lymphatic,  thymus,  and  thyroid  glands,  lungs,  and  liver.  Pathologi- 
cally, its  quantity  in  the  liver  is  much  increased  in  diseases  of  that  organ, 
and  in  typhus  and  variola;  in  the  bile  in  typhus,  in  the  blood  in  leucocy- 
thasmia,  and  in  yellow  atrophy  of  the  liver;  in  the  urine  in  yellow  atrophy 
of  the  liver,  in  typhus,  and  in  variola;  in  choleraic  discharges  from  the 
intestine,  in  pus,  in  the  fluids  of  dropsy,  and  of  atheromatous  cysts.  In 
these  situations  it  is  usually  accompanied  by  tyrosine  (q.  v.).  It  is  much 
more  abundant  in  the  tissues  of  the  lower  forms  of  animal  life,  and  has 
aiso  been  found  in  vegetable  tissues. 

It  is  formed  by  the  decomposition  of  nitrogenized  animal  and  vege- 
table substances  by  heating  with  strong  alkalies  or  dilute  acids;  by  the 
decomposition  of  elastic  tissues  it  is  formed  with  a  small  quantity  of 
tyrosine;  by  that  of  gelatinoid  materials,  leucine  and  glycine  are  obtained; 
by  that  of  albuminoids,  leucine  and  a  small,  but  variable,  quantity  of  tyro- 
sine are  formed;  and  that  of  epidermic  tissues  yields  leucine  and  tyrosine. 
It  is  also  one  of  the  products  of  the  putrefaction  of  animal  and  vegetable 
albuminoids,  and  of  the  action  of  pancreatic  juice  upon  fibrin.  It  has  also 
been  formed  synthetically  by  the  action  of  ammonia  upon  bromocaproic 
acid  in  the  same  way  that  alanine  is  formed  from  bromopropionic  acid 
(see  above). 

It  may  be  obtained  by  a  variety  of  methods,  the  most  advantageous  of 
which  consists  in  boiling  one  part  of  horn-shavings  with  four  parts  of  sul- 
phuric acid  and  twelve  parts  of  water,  for  thirty-six  hours,  renewing  the 
water  as  it  evaporates;  the  acid  liquid  is  saturated  with  milk  of  lime 
and  boiled  again  for  twenty-four  hours;  it  is  then  filtered  through  linen, 
a  slight  excess  of  sulphuric  acid  is  added,  and  the  liquid  again  filtered  and 
evaporated;  tyrosine  first  crystallizes  out  and  is  separated,  after  which 
leucine  separates  in  crystals,  which  are  purified  by  recrystallization  from  a 
small  quantity  of  water,  the  crystals  first  formed  being  rejected  as  being 
contaminated  with  tyrosine.  The  leucine  so  obtained  is  further  purified 
by  solution  in  hot  water,  digestion  with  lead  hydrate;  filtration,  treatment 
with  hydrogen  sulphide;  filtration,  treatment  with  animal  charcoal;  filtra- 
tion and  crystallization. 

Leucine  crystallizes  from  alcohol  in  soft,  pearly  plates,  lighter  than 
water,  and  somewhat  resembling  cholesterin;  sometimes  in  round  masses 
composed  of  closely  grouped  needles  radiating  from  a  centre.  It  is  spar- 
ingly soluble  in  cold  water;  readily  in  warm  water;  almost  insoluble  in 
cold  alcohol  and  ether;  soluble  in  boiling  alcohol,  which  deposits  it  on 
cooling;  it  is  odorless  and  tasteless,  and  its  solutions  are  neutral.  Its  sol- 
ubility in  water  is  increased  by  the  presence  of  acetic  acid  or  of  potassium 
acetate.  It  sublimes  at  170°  without  decomposition;  if  suddenly  heated 
above  180°,  it  is  decomposed  into  amylamine  and  carbon  dioxide. 

When  heated  to  140°  with  hydriodic  acid  under  pressure,  it  is  decom- 
posed into  caproic  acid  and  ammonia.  Nitrous  acid  converts  it  into  leucic 
acid,  CBH12O3,  water,  and  nitrogen.  It  unites  with  acids  to  form  soluble 
crystalline  salts.  It  also  dissolves  readily  in  solutions  of  alkaline  hydrates, 
forming  crystalline  compounds  with  the  metallic  elements. 

The  formation  of  leucine  in  the  body  is  one  of  the  steps  of  the  trans- 
formation of  at  least  some  part  of  the  albuminoids  into  urea.  That  leu- 
cine is  formed  at  the  expense  of  the  albuminoids  by  some  fermentation- 
like  process,  there  can  be  no  doubt;  as  it  is  only  discharged  in  the  urine 
in  certain  exceptional  pathological  conditions,  and  as  at  the  same  time  the 


216  GENERAL    MEDICAL    CHEMISTRY. 

elimination  of  urea  is  greatly  diminished,  it  seems  highly  probable  that 
under  normal  conditions  the  nitrogen  of  leucine  finally  makes  its  exit  from 
the  body  as  urea,  notwithstanding  the  fact  that  chemists  have  hitherto 
been  unable  to  obtain  urea  from  leucine  artificially.  As  to  the  nature  of 
the  changes  by  which  leucine  is  converted  into  urea  in  the  body,  we  are 
as  yet  in  the  dark. 

When  leucine  and  tyrosine  appear  in  the  urine,  that  fluid  is  poor  in 
urea  and  usually  contains  biliary  coloring  ^matters;  the  substitution  of 
leucine  for  urea  may  be  so  extensive  that  the  urine  contains  no  urea,  and 
contains  leucine  in  such  quantity  that  it  crystallizes  out  spontaneously. 

The  presence  of  smaller  quantities  of  leucine  and  tyrosine  in  the 
urine  may  be  detected  as  follows:  the  freshly  collected  urine  is  treated 
with  basic  lead  acetate,  filtered,  the  filtrate  treated  with  hydrogen  sul- 
phide, filtered  from  the  precipitated  lead  sulphide,  and  the  filtrate  evap- 
orated over  the  water-bath;  leucine  and  tyrosine  crystallize;  they  may 
be  separated  by  extraction  of  the  residue  with  hot  alcohol,  which  dissolves 
the  leucine  and  leaves  the  tyrosine.  The  leucine  left  by  evaporation  of 
the  alcoholic  solution  may  be  recognized  by  its  crystalline  form  and  by 
the  following  characters  :  1st,  a  small  portion  is  moistened  on  platinum 
foil  with  nitric  acid,  which  is  then  cautiously  evaporated;  a  colorless  res- 
idue remains,  which,  when  warmed  with  caustic  soda  solution,  turns  yel- 
low or  brown,  and  by  further  concentration  is  converted  into  oily  drops, 
which  do  not  adhere  to  the  platinum  (Scherer's  test);  2d,  a  portion 
of  the  residue  is  heated -in  a  dry  test-tube;  it  melts  into  oily  drops,  and 
the  odor  of  amylamine  (odor  of  ammonia  combined  with  that  of  fusel  oil) 
is  observed;  3d,  if  a  boiling  mixture  of  leucine  and  solution  of  neutral 
lead  acetate  be  carefully  neutralized  with  ammonia,  brilliant  crystals  of  a 
compound  of  leucine  and  lead  oxide  separate;  4th,  leucine  carefully 
heated  in  a  glass  tube  open  at  both  ends,  to  170°,  sublimes  without  fus- 
ing, and  condenses  in  flocculent  shreds,  resembling  those  of  sublimed 
zinc  oxide.  If  heated  beyond  180°,  the  decomposition  mentioned  in  3d 
occurs. 

Tyrosine,  C9HUNO3. 

A  substance  which  certainty  does  not  belong  to  this  series,  and  is 
probably  an  amido-acid  of  the  aromatic  series;  nevertheless,  as  its  consti- 
tution is  still  undetermined,  and  as  it  is  almost  universally  found  to  ac- 
company leucine  in  animal  tissues  and  in  the  products  of  their  decompo- 
sition, it  may  be  considered  in  -this  place. 

The  methods  of  its  formation  and  preparation  are  given  under  leu- 
cine. 

It  crystallizes  from  its  watery  and  ammoniacal  solutions  in  silky  nee- 
dles, arranged  in  stellate  bundles;  very  sparingly  soluble  in  cold  water; 
almost  insoluble  in  alcohol;  more  soluble  in  hot  water.  When  heated  it 
turns  brown  and  yields  an  oily  matter  having  the  odor  of  phenol;  when 
heated  in  small  quantities  to  270°,  it  is  decomposed  into  carbon  dioxide 
and  a  white  solid,  having  the  composition  C8HnNO,  which  sublimes.  It 
combines  with  both  acids  and  bases. 

It  has  been  found  in  animal  nature  in  the  same  situations  as  leucine. 
When  taken  into  the  stomach  it  is  not  altered  in  the  economy,  but  is  elim- 
inated in  the  urine  and  faeces. 

Tyrosine  may  be  recognized  by  the  following  characters:  1st,  its  crv-s- 
talline  form;  3d,  when  heated  it  does  not  sublime,  but  gives  off  an  odor 


CREATININE.  217 

resembling  that  of  phenol;  3d,  when  moistened  on  platinum  foil  with 
nitric  acid  and  this  carefully  evaporated,  it  dissolves  and  leaves  a  deep  yel- 
low residue,  which,  when  moistened  with  sodic  hydrate  solution,  turns 
deep  yellowish  red  and  leaves,  on  evaporation  of  the  soda,  a  dark  brown 
residue  (Scherer);  4th,  when  moistened  on  a  porcelain  dish  with  con- 
centrated sulphuric  acid  and  slightly  warmed,  it  dissolves  with  a  transient 
red  color;  the  solution,  diluted  with  water,  neutralized  with  calcium  car- 
bonate and  filtered,  gives  a  liquid  to  which  a  neutral  solution  of  ferric 
chloride  communicates  a  fine  violet  color  (Piria) ;  5th,  if  boiled  with  a 
solution  of  acid  nitrate  of  mercury,  a  pink  color  is  first  observed,  and  later 
.a  red  precipitate  (Hoffmann,  L.  Meyer). 


Creatine,  C4H9N3O2+Aq. 

Another  complex  amido-acid,  which  occurs  as  a  normal  constituent  of 
the  juices  of  muscular  tissue,  voluntary  and  involuntary,  of  brain,  blood, 
and  amniotic  fluid.  Its  existence  in  the  urine  is  very  doubtful. 

It  is  best  obtained  from  the  flesh  of  the  fowl,  which  contains  0.32  per 
cent.,  or  from  beef-heart,  which  contains  0.14  per  cent.,  by  hashing, 
warming  with  alcohol  and  expressing  strongly;  the  alcohol  is  distilled  off, 
the  residual  liquid  precipitated  with  lead  acetate,  filtered,  treated  with 
hydrogen  sulphide,  again  filtered,  the  filtrate  evaporated  to  a  syrup,  from 
which  the  creatine  crystallizes. 

It  is  soluble  in  boiling  water  and  in  alcohol,  insoluble  in  ether;  crys- 
tallizes in  brilliant,  oblique,  rhombic  prisms;  neutral,  tasteless,  loses  aq. 
at  100°;  fuses  and  decomposes  at  higher  temperatures. 

W^hen  long  heated  with  water  or  treated  with  concentrated  acids,  it 
loses  H2O,  and  is  converted  into  creatinine.  Baryta  water  decomposes  it 
into  sarcosine  and  urea.  It  is  not  precipitated  by  silver  nitrate,  except 
when  it  is  in  excess  and  in  presence  of  a  small  quantity  of  potassium 
hydrate;  the  white  precipitate  so  obtained  is  soluble  in  excess  of  potash, 
from  which  a  jelly  separates  which  turns  black,  slowly  at  ordinary  tem- 
peratures, rapidly  at  100°.  A  white  precipitate,  which  turns  black  when 
heated,  is  also  formed  when  a  solution  of  creatine  is  similarly  treated  with 
mercuric  chloride  and  potash. 

Creatin  is  undoubtedly  an  intermediate  product  of  disassimilation  of 
the  albuminoid  constituents  of  the  tissues  in  which  it  occurs;  it  is  not  dis- 
charged as  such,  but  only  after  decomposition  into  creatinine  and  into  urea, 
both  of  which  increase  in  quantity  in  the  urine  when  creatine  is  taken. 


Creatinine,  C4H7N3O. 

A  product  of  the  dehydration  of  creatine,  is  a  normal  and  constant 
constituent  of  the  urine  and  amniotic  fluid,  and  has  also  been  found  to 
exist  in  the  blood  and  muscular  tissue. 

It  crystallizes  in  oblique,  rhombic  prisms,  soluble  in  water  and  in  hot 
alcohol;  insoluble  in  ether.  It  is  a  strong  base,  has  an  alkaline  taste  and 
reaction,  expels  ammonia  from  the  ammoniacal  salts,  and  forms  well-defined 
salts,  among  which  is  the  double  chloride  of  zinc  and  creatinine  (C4II7 
N3O)2ZnCl2,  obtained  in  very  sparingly  soluble,  oblique  prismatic  crystals, 
when  alcoholic  solutions  of  creatinine  and  zinc  chloride  are  mixed. 


218  GENERAL    MEDICAL    CHEMISTRY. 

The  quantity  of  creatinine  eliminated  is  slightly  greater  than  that  of  uric 
acid,  0.6 — 1.3  gram  in  twenty-four  hours;  it  is  not  increased  by  muscular 
exercise,  but  is  diminished  in  progressive  muscular  atrophy.  It  is  obtained 
from  the  urine  by  precipitation  with  zinc  chloride. 


COMPOUNDS     OP     THE     ALCOHOLIC     RADICALS    WITH 
OTHER  ELEMENTS. 

The  organic  substances  hitherto  considered  are  composed  of  seven 
elements  only:  carbon,  hydrogen,  oxygen,  nitrogen,  chlorine,  bromine, 
and  iodine;  but  compounds  of  carbon  containing  every  known  element  have 
been  observed  to  exist  in  nature,  or  have  been  produced  artificially.  Of 
these  quite  a  number  may  be  considered  as  containing  the  radicals  of  the 
series  CnII.M4ij,  which  exist  in  the  monoatomic  alcohols.  These  bodies  are 
almost  exclusively  the  products  of  the  laboratory,  and  resemble  in  consti- 
tution some  of  the  compounds  already  considered. 

Sulphides. — The  compounds  of  the  alcoholic  radicals  with  sulphur 
are  the  same  in  constitution  as  those  with  oxygen,  sulphur  taking  the 
place  of  oxygen: 

>"    p'S5[°"    c^\s"    r2iHs" 

W11,    )  M    )  ^a11*    ) 

Ethyl  hydrate  Ethyl  oxide  Ethyl  sulphydrate        .Ethyl  sulphide, 

(alcohol).  (ether).  (mercoptan). 

Similar  compounds  have  been  obtained  in  Avhich  the  oxygen  is  replaced 
by  tellurium  or  by  selenium. 

Ethyl  sulphydrate^  usually  known  as  tnercaptan^  from  its  tendency  to 
unite  with  mercury  (corpus  mercurium  captans),  is  formed  in  a  great 
variety  of  reactions.  It  is  best  prepared  by  treating  alcohol  with  sul- 
phuric acid,  as  in  the  preparation  of  sulphovinic  acid  (q.  -y.),  mixing  the 
crude  product  with  excess  of  potash,  separating  from  the  crystals  of  potas- 
sium sulphate,  saturating  with  hydrogen  sulphide,  and  distilling. 

It  is  a  mobile,  colorless  liquid;  sp.  gr.  0.8325,  at  21°;  has  an  intensely 
disagreeable  odor,  combined  of  those  of  garlic  and  sulphuretted  hydrogen; 
boils  at  36.2°;  ignites  readily  and  burns  with  a  blue  flame;  may  be  readily 
frozen  by  the  cold  produced  by  its  own  evaporation;  neutral  in  reaction; 
sparingly  soluble  in  water,  soluble  in  all  proportions  in  alcohol  and  ether; 
dissolves  iodine,  sulphur,  phosphorus. 

Potassium  and  sodium  act  with  mercaptan  as  with  alcohol,  replacing 
the  extra-radical  hydrogen.  In  its  behavior  toward  the  oxides  it  more 
closely  resembles  the  acids  than  the  alcohols,  being  capable  even  of  enter- 
ing into  double  decomposition  to  form  salts,  called  sulphethylates  or  mer- 
eaptides.  Its  action  with  mercuric  oxide  is  characteristic,  forming  a 
white,  crystalline  sulphide  of  ethyl  and  mercury: 


Ethyl  sulphydrate.  Mercuric  oxide.    Ethyl-mercurial  sulphide.  Water. 

It  forms  similar  compounds  with  gold  and  platinum. 

Ethyl  sulphide,  a  colorless  liquid;  having  a  penetrating,  disagreeable 
odor  of  garlic;  boiling  at  73°;  insoluble  in  water,  soluble  in  alcohol;  in- 


COMPOUNDS    OF    THE    ALCOHOLIC    RADICALS.  219 

flammable;  obtained  by  the  action  of  ethyl  chloride  upon  potassium  sul- 
phide. 

Phosphines,  arsines,  and  stibines  are  compounds  resembling  the 
amines  in  constitution,  in  which  the  nitrogen  is  replaced  by  phosphorus, 
arsenic,  or  antimony;  like  the  amines,  they  may  be  primary,  secondary, 
or  tertiary: 

C,H5  )  C2H5 

OH  f  AS       a  H;  5.  sb. 


H 


Ethylamine  Ethylphospine  Diethyl-arsine  Triethyl-stibine 

(primary).  (primary).  (secondary).  (tertiary). 

There  also  exist  compounds  containing  phosphorus,  antimony,  or  arse- 
nic, which  are  similar  in  constitution  to  the  hydrates  and  salts  of  ammo- 
nium, and  of  the  compound  ammoniums: 

NH4I  N(CH3)4I  As(CH3)4I 

Ammonium  Tetramethyl  ammonium         Tetramethyl  arsenium 

iodide.  iodide.  iodide. 

Most  of  these  compounds,  which  are  very  numerous,  are  as  yet  only 
of  theoretic  interest.  One  of  them,  however,  is  deserving  of  notice  here: 


CH3) 
Dimethyl  arsine,  CH3  v  As  —  which   may  be  considered  as  being  the 

H  ) 

hydride  of  the  radical  [As  (CH3)2],  does  not  exist  as  such;  there  was,  how- 
ever, discovered  by  Cadet,  in  1760,  a  liquid  known  as  the  fuming  liquor 
of  Cadet,  or  alkarsin,  which  he  obtained  by  distilling  a  mixture  of  potas- 
sium acetate  and  arsenic  trioxide.  This  liquid  was  made  the  subject  of 
most  successful  study  by  Bunsen,  who  found  that  it  contained  the  oxide 
of  the  above  radical,  and  a  substance  which  ignited  on  contact  with  air, 
and  which  consists  of  the  same  radical  united  to  itself  2  [As  (CH3)2],  He 
subsequently  found  that  this  radical,  to  which  he  gave  the  name  of  caco- 
dyle  (K<XKOS  =  evil),  was  capable  of  entering  into  a  great  number  of  other 
combinations.  Cacodyle  and  its  compounds  are  all  exceedingly  poison- 
ous, especially  the  cyanide,  an  ethereal  liquid,  very  volatile,  the  presence 
of  whose  vapor  in  inspired  air,  even  in  minute  traces,  produces  symptoms 
referable  both  to  arsenic  and  to  hydrocyanic  acid. 

Organo-metallic  substances  are  compounds  of  the  alcoholic  radi- 
cals with  that  class  of  elements  usually  designated  as  metallic.  They 
are  very  numerous,  usually  obtained  by  the  action  of  the  iodide  of  the 
alcoholic  radical  upon  the  metallic  element,  in  an  atmosphere  of  hydrogen. 
They  are  substances  which,  although  they  have  been  put  to  no  uses  in 
the  arts  or  in  medicine,  have  been  of  great  practical  service  in  chemical 
research.  As  typical  of  this  class  of  substances  we  may  mention: 

Zinc-ethyl,  ri2TT5  !•  Zn  —  a  substance  discovered  in  1849,  by  Frankland. 

It  is  obtained  by  heating  at  130°  in  a  sealed  tube  a  mixture  of  perfectly 
dry  zinc  amalgam  with  ethyl  iodide;  the  contents  of  the  tube  are  then 
distilled  in  an  atmosphere  of  coal-gas,  or  hydrogen,  and  the  distillate 
collected  in  a  receiver,  in  which  it  can  be  sealed  by  fusion  of  the  glass- 
without  contact  with  air. 


220  GENERAL    MEDICAL    CHEMISTRY. 

It  is  a  colorless,  transparent,  highly  refracting  liquid;  sp.  gr.  1.182; 
boils  at  118°.  On  contact  with  air  it  ignites  and  burns  with  a  luminous 
flame,  bordered  with  green,  and  gives  off  dense  clouds  of  zinc  oxide,  a 
property  which  renders  it  very  dangerous  to  handle.  With  carbon  dioxide 
it  combines  to  form  zinc  propionate: 

Zn  (C2H5)2      +     2C02  (C3H502)2Zn. 

Zinc  ethyl.  Carbon  dioxide.  "          Zinc  propionate. 

On  contact  with  water  it  is  immediately  decomposed  into  zinc  hydrate 
and  ethyl  hydride.  It  is  chiefly  useful  as  an  agent  by  which  the  radical 
ethyl  can  be  introduced  into  organic  molecules;  thus,  by  the  action  of 
zinc  ethyl  upon  acetyl  chloride,  a  compound  of  acetyl  and  ethyl  is  ob- 
tained : 


Zn(C2H5)2     +     2C2H3OC1     = 

Zinc-ethyl.  Acetyl  chloride.  Zinc  chloride.  Acetyl-ethyl. 


ALLYLIC  SERIES. 

The  compounds  which  we  have  heretofore  considered  may  be  derived 
more  or  less  directly  from  the  saturated  hydrocarbons;  in  the  derivatives, 
as  in  the  hydrocarbons,  the  valences  of  the  carbon  atoms  are  all  satisfied, 
and  that  in  the  simplest  and  most  complete  manner,  two  neighboring 
atoms  of  carbon  always  exchanging  a  single  valence.  There  exist,  how- 
ever, other  compounds,  containing  less  hydrogen  in  proportion  to  carbon 
than  those  already  considered,  and  yet  resembling  them  in  being  mono- 
atomic.  These  compounds  have  usually  been  considered  as  non-saturated ', 
because  all  the  possible  valences  are  not  satisfied,  and  the  substances  are 
therefore  capable  of  forming  products  of  addition,  while  the  saturated 
compounds  can  only  form  products  of  substitution. 

In  this  sense  the  substances  composing  this  series  are  non-saturated, 
but  they  are  not  so  in  the  sense  that  they  contain  carbon  or  other  atoms 
whose  valences  are  not  satisfied.  The  following  formulae  indicate  the 
constitution  of  the  substances  of  this  series,  and  their  relation  to  those 
of  the  previous  one.  It  will  be  observed  that  in  the  allyl  compounds  two 
neighboring  atoms  of  carbon  exchange  two  valences: 


CH3  CH3  CH3  CH3 

CH2  CH2  OH,  OH, 


CH2H          CH2OH  COH  0 


OOH 


CH 


or  or  or  or 

\ 


Propyl  hydride        Propyl  hydrate         Propionyl  hydride     Propionyl  hydrate  Propyl 

(hydrocarbon).  (alcohol).  (aldehyde).  (acid).  (radical). 


ALLYLIC    SERIES. 


221 


fCH,l 

I! 
CH 


T-l, 


or 
C3H5  I 

o'X  f 

Diallyl 
(hydrocarbon) . 


CH, 

II 
CH 

CH3OH 


CHa 

II 
CH 

COH 


or 


Allyl  hydrate 
(alcohol). 


CH2 

II 
CH 

COOH 

or 


CHJ 

II 
OH 

in. 


Acrolein 
(aldehyde). 


Acrylic  acid 
(acid). 


Allyl 
(radical). 


C1  TT    ) 
Diallyl,   p3Tj5  [  — formerly  known  as  allyl,  is  obtained  by  the  action 

of  sodium  upon  allyl  iodide,  and  is  not,  as  its  empirical  formula  would 
seem  to  indicate,  a  superior  homologue  of  acetylene  and  allylene  (q.  v.). 

It  is  a  colorless  liquid,  having  a  peculiar  odor,  somewhat  resembling 
that  of  horseradish;  boils  at  59°;  sp.  gr.  0.684  at  14°;  burns  with  a  lumi- 
nous flame. 

Allyl  iodide,  C3H5I — is  a  colorless  liquid,  having  an  ethereal,  alli- 
aceous odor;  boiling  at  101°;  sp.  gr.  1.789  at  16°;  obtained  by  the  action 
of  phosphorus  triiodide  upon  either  allylic  alcohol  or  glycerin. 

Allyl  hydrate — Allylic  alcohol —    8  j|  j-  O — may  be  obtained  by  a 

variety  of  methods: 

First. — By  the  action  of  silver  oxalate  upon  allyl  iodide,  allyl  oxalate 
is  formed;  this  is  then  decomposed  with  ammonia,  and  oxamide  and  allyl 
hydrate  are  obtained. 

Second. — By  the  action  of  sodium  upon  dichlorhydrine  in  ethereal 
solution. 

Third. — The  best  process  consists  in  heating  four  parts  of  glycerin 
with  one  part  of  crystallized  oxalic  acid.  In  the  first  stage  of  the  oper- 
ation carbon  dioxide  is  given  off  abundantly;  as  the  temperature  rises 
the  formation  of  carbon  dioxide  diminishes,  and  again  increases  at  about 
190°,  when  allyl  alcohol  begins  to  be  formed;  at  this  time  the  receiver 
connected  with  the  retort,  in  which  the  mixture  is  heated,  is  changed, 
and  the  heat  increased  to  about  260°.  The  product,  which  is  a  mixture 
of  allyl  alcohol  with  allyl  formiate,  formic  acid,  acrolein,  and  glycerin,  is 
purified  by  agitation  with  sodium  carbonate  and  with  caustic  potassa, 
after  which  it  is  rectified,  and  finally  distilled  from  quicklime. 

Allylic  alcohol  is  a  colorless,  mobile  liquid;  solidifies  at  — 54°;  boils 
at  97°;  sp.  gr.  0.8507  at  25°;  soluble  in  water;  has  an  odor  resembling 
the  combined  odors  of  alcohol  and  essence  of  mustard;  burns  with  a 
luminous  flame. 

Allyl  alcohol  is  isomeric  with  propylic  aldehyde  and  with  acetone. 
Being  an  unsaturated  compound,  it  is  capable  of  forming  products  of 
addition  with  chlorine,  bromine,  and  iodine,  etc.,  which  are  isomeric  or 
identical  with  products  of  substitution  obtained  by  the  action  of  the  same 
elements  upon  glycerin  (see  Glycerides,  p.  277).  Oxidizing  agents  con- 
vert it  first  into  acrolein,  acrylic  aldehyde,  C3H4O,  and  finally  into  acrylic 
acid.  It  does  not  combine  readily  with  hydrogen,  but  in  the  presence  of 
nascent  hydrogen  combination  takes  place  slowly,  with  formation  of  pro- 
pylic alcohol. 


222  GENERAL    MEDICAL    CHEMISTRY. 

O  TT   ) 
Allyl  oxide—  Allylic  ether  —  Q3jj5  r  O  —  exists   in  small  quantities  in 

crude  essence  of  garlic.  It  is  obtained  as  a  colorless  liquid,  having  an 
alliaceous  odor;  insoluble  in  water;  boiling  at  82°,  by  a  number  of  reac- 
tions, but  best  by  the  action  of  allyl  iodide  upon  sodium  allyl  oxide: 


Allyl  iodide.  Sodium  ally)  Sodium  iodide.  Allyl 

oxide. 

C^  TT    i 
Allyl  sulphide  —  Essence  of  garlic  —  Qjr5  [  S  —  is  obtained  by  the  ac- 

tion of  an  alcoholic  solution  of  potassium  sulphide  upon  allyl  iodide;  also 
as  a  constituent  of  the  volatile  oil  of  garlic,  by  macerating  garlic,  or 
other  related  vegetables,  in  water  and  distilling.  Crude  essence  of  garlic 
is  thus  obtained  as  a  heavy,  fetid,  brown  oil;  this  is  purified  by  redis- 
tillation below  140°;  contact  with  potassium  and  subsequent  redistillation 
form  calcium  chloride. 

As  thus  obtained  it  is  a  colorless,  transparent  oil;  lighter  than  water, 
sparingly  soluble  in  water,  very  soluble  in  alcohol  and  ether;  boils  at  140°; 
has  an  intense  odor  of  garlic. 

This  substance  does  not  exist  naturally  in  the  plant,  or  at  least 
not  in  quantities  at  all  approximating  to  those  in  which  it  is  obtained  from 
it;  it  is  formed  during  the  process  of  extraction  by  the  action  of  water, 
probably  in  a  manner  similar  to  that  in  which  essence  of  mustard  is  formed 
under  similar  circumstances.  It  is  to  the  formation  of  allyl  sulphide, 
which  is  highly  volatile,  that  garlic  owes  the  odor  which  it  emits,  espe- 
cially when  heated  with  water,  as  in  cooking. 

CN  ) 
Allyl  sulphocyanate  —  Essential  oil  of  mustard  —  ^  TJ   j-  S.  —  If  the 

seeds  of  white  or  black  mustard  be  strongly  expressed,  a  bland,  neutral  oil 
is  obtained,  which  resembles  rapeseed  and  colza  oils  in  its  physical  prop- 
erties, and  in  being  composed  of  the  glycerides  of  stearic,  oleic  and  erucic 
acids.  The  cake  remaining  after  the  expression  of  this  oil  from  black 
mustard,  or  the  black-mustard  seeds  themselves,  pulverized  and  mois- 
tened with  water,  gives  off  a  strong,  pungent  odor.  If  the  water  be  now 
distilled,  a  volatile  oil  passes  over  with  it,  which  is  the  crude  essential 
oil  of  mustard. 

In  practice  the  powdered  cake  of  black-mustard  seeds,  from  which  the 
fixed  oil  has  been  expressed,  is  digested  with  four  to  six  parts  of  water  for 
twenty-four  hours,  after  which  the  water  is  distilled  as  long  as  any  oily 
matter  passes  over;  the  oil  is  collected,  dried  by  contact  with  calcium 
chloride,  and  redistilled.  Essence  of  mustard  may  also  be  obtained  syn- 
thetically by  the  action  of  allyl  bromide  or  iodide  upon  potassium  sulpho- 
cyanate, or  by  the  action  of  allyl  iodide  upon  silver  sulphocyanate. 

This  essence  does  not  exist  preformed  in  the  mustard,  but  results  from 
the  decomposition  of  a  peculiar  constituent  of  the  seeds,  potassium  myro- 
nate,  determined  by  a  fermentation  set  up  by  another  constituent,  myro- 
sine,  in  the  presence  of  water  —  the  decomposition  probably  occurring 
according  to  the  equation  — 

C1^1.NS,01.K     =      CNS,C3H5     +      C8H,A     +      SO,HK 

PotaRsium  myronate.  Allyl  sulphocyanate.  Glucose.  Hydropotassic 

sulphate. 


ACIDS    AND    ALDEHYDES    OF   THE    ACRYLIC    SERIES. 


223 


Potassium  myronate  exists  only  in  appreciable  quantity  in  the  black 
variety  of  mustard,  from  which  it  may  be  obtained  in  the  shape  of  short, 
prismatic  crystals,  transparent,  odorless,  bitter;  very  soluble  in  water, 
sparingly  so  in  alcohol. 

Myrosine  is  a  nitrogenized  ferment  existing  in  the  white  as  well  as 
in  the  black  mustard,  and  in  other  seeds.  It  may  be  obtained  from  white- 
mustard  seeds,  in  an  impure  form,  by  extraction  with  cold  water,  filtering 
and  evaporating  the  solution  at  a  temperature  below  40°;  the  syrupy 
fluid  so  obtained  is  precipitated  with  alcohol,  the  precipitate  washed 
with  alcohol,  redissolved  in  water,  and  the  solution  evaporated  below  40° 
to  dryness. 

At  temperatures  above  40°  myrosine  becomes  coagulated  and  inca- 
pable of  decomposing  potassium  myronate,  a  change  which  is  also  pro- 
duced by  contact  with  acetic  acid.  As  the  rubefacient  and  vesicant 
actions  of  mustard,  when  moistened  with  water,  are  due  to  the  production 
of  allyl  sulphocyanate,  it  is  obvious  that  neither  vinegar,  acetic  acid, 
or  heat  greater  than  40°,  should  be  used  in  the  preparation  of  mustard 
cataplasms.  The  prepared  mustard  plasters  or  papers  which  are  now  in 
use  are  made  by  spreading  the  flour  of  mustard,  mixed  with  benzol  or 
carbon  disulphide  and  caoutchouc,  upon  paper. 

Pure  allyl  sulphocyanate  is  a  transparent,  colorless  oil;  sp.  gr.  1.015 
at  20°;  boils  at  143°;  has  a  penetrating,  pungent  odor,  sparingly  soluble 
in  water,  very  soluble  in  alcohol  and  ether.  When  exposed  to  the  light  it 
gradually  turns  brownish  yellow  and  deposits  a  resinoid  material.  When 
applied  to  the  skin  it  produces  rubefaction,  quickly  followed  by  vesication. 

Menthyl  hydrate — Menthol — Menthic  alcohol — Peppermint  cam- 

C  H    ) 
phor —    10   H  I  ^ — *s  a  suPeri°r  homologue  of  allyl  alcohol,  and  is  a  solid 

deposited  by  the  essential  oil  of  peppermint.  When  purified  it  forms  color- 
less, prismatic  crystals;  insoluble  in  water,  soluble  in  alcohol,  ether,  and 
in  acids;  fuses  at  34° — 36°;  boils  at  213°;  has  the  odor  and  taste  of  pep- 
permint strongly  developed.  It  is  capable  of  yielding,  under  suitable 
conditions,  ethers  of  a  radical,  menthyl,  and  a  hydrocarbon — menthene, 

CTT 

10^8' 


ACIDS  AND  ALDEHYDES  OP  THE  ACRYLIC  SERIES. 

These  substances  bear  the  same  relation  to  the  alcohols  of  the  allyl 
series  that  the  volatile  fatty  acids  and  the  corresponding  aldehydes  bear 
to  the  ethylic  series  of  alcohols.  The  following  terms  of  the  series  have 
been  obtained: 


Acids. 


Acrylic  acid  ..............  C3O2H4 

Crotonic  ................  C4O2H 

Angelic  .................  C5O2H8 

Pyroterebic  .............  Cfi(XHlfl 

Oleic  ..................  C1802H34 


Aldehydes. 
CnH2n_20. 

Acrolein C3OH4 

Crotonic  aldehyde C4OH6 


The  acids  of  this  series  differ  from  those  containing  the  same  number 
of  carbon  atoms  in  the  formic  series,  by  containing  two  atoms  of  hydro- 


224  GENERAL    MEDICAL    CHEMISTRY. 

gen  less;  they  are  readily  converted  into  acids  of  the  formic  series  by 
the  action  of  potassium  in  fusion,  which  forms  with  them  the  potassium 
salt  of  acetic  acid  and  that  of  the  acid  of  the  formic  series  containing* 
the  complementary  number  of  carbon  atoms,  thus: 

C3H402     +     2KHO     =     C2H302K     +      CHO2K       +     H, 

Acrylic  acid.  V         Acetate.  Formiate. 

O  TT  O  ) 
Acrylic   acid —    3    Yr  !•  O  — is  obtained   by   oxidation  of  acrolein, 

acrylic  aldehyde,  by  silver  oxide,  and  is  formed  in  a  number  of  other  re- 
actions; as  a  product  of  the  oxidation  of  acrolein,  it  is  formed  when  grease 
is  strongly  heated. 

It  is  a  colorless,  highly  acid  liquid;  has  a  penetrating  odor;  solidifies 
at  7°;  boils  at  140°;  distils  unchanged  with  vapor  of  water. 

Nascent  hydrogen  unites  with  it  to  form  proprionic  acid.  It  readily 
forms  crystallized  salts  and  ethers.  There  exist  products  of  substitution 
with  chlorine  and  bromine. 

Acrylic  aldehyde — Allylic  aldehyde — Acrolein — C3H3O  )    _  ^, 

H  )  " 

the  fats  and  fixed  oils  are  decomposed  by  heat,  a  disagreeable,  irritating 
odor  is  produced,  which  is  due  to  the  formation  of  acrolein  by  the  dehy- 
dration of  the  glycerin  contained  in  the  fatty  material.  Acrolein  may 
be  obtained  by  heating  glycerin  with  strong  sulphuric  acid,  or  with  hy- 
dropotassic  sulphate.  Glycerin  is  the  alcohol  (hydrate)  of  a  radical  hav- 
ing the  same  composition  as  allyl,  but  so  differing  from  it  in  constitution 
as  to  be  trivalent  in  place  of  univalent. 

(C3H5)'"(OH)3     =     2H20     +     (C3H30)'H 

Glycerin.  Water.  Acrolein. 

The  condensed  product  of  this  reaction,  which  must  be  conducted  in 
an  atmosphere  of  carbon  dioxide,  in  a  capacious  retort  and  receiver,  and 
in  such  a  way  that  the  uncondensed  products  are  discharged  into  the 
open  air,  are  purified  by  contact  with  lead  oxide,  and  subsequent  distilla- 
tion from  calcium  chloride. 

Acrolein  is  a  colorless,  limpid  liquid;  lighter  than  water;  boils  at  52.4°; 
sparingly  soluble  in  water;  more  soluble  in  alcohol  ;  very  volatile,  its 
vapor  having  a  very  pungent  odor  and  producing  irritation  and  suffoca- 
tion to  such  a  degree  that  the  presence  of  a  very  small  quantity  in  a  con- 
fined space  renders  the  atmosphere  irrespirable  ;  its  taste  is  caustic. 
When  freshly  prepared  it  is  neutral  in  reaction,  but  on  contact  with  air  it 
rapidly  becomes  acid  by  oxidation.  For  the  same  reason  it  does  not  keep 
well,  even  in  closed  vessels;  on  standing  it  deposits  a  flocculent  material, 
which  has  been  called  disocryl,  while  at  the  same  time  formic,  acetic,  and 
acrylic  acids  are  formed. 

Oxidizing  agents  convert  acrolein  into  acrylic  acid,  or,  if  they  be  ener- 
getic, into  a  mixture  of  formic  and  acetic  acids.  The  caustic  alkalies 
produce  from  it  resinoid  substances  similar  to  those  formed  from  acetic 
aldehyde.  With  ammonia  it  forms  a  crystalline,  odorless  compound, 
which  behaves  as  a  base. 

Acrolein  is  formed  whenever  glycerin,  or  any  substance  containing  it 
or  its  compounds  with  the  fatty  acids,  is  heated  to  a  temperature  sufficient 


ACIDS    AND    ALDEHYDES    OF   THE    ACRYLIC   SERIES.          225 

to  effect  its  decomposition;  for  this  reason,  and  because  of  the  irritating 
action  of  the  acrolein,  the  heavy  petroleum-oils  are  preferable  to  those  of 
vegetable  or  animal  origin  for  the  lubricating  of  machinery  operated  in  en- 
closed places. 

r1  TT  o ) 

Crotonic  acid,     *    Vr  [•  O — was  first  obtained  from  croton-oil,  oleum 

tiglii  (U.  S.),  in  which  it  exists  in  combination  with  glycerin,  and  accom- 
panied by  the  glycerin  ethers  of  several  other  fatty  acids;  it  is,  however, 
neither  the  vesicant  nor  the  purgative  principle  of  the  oil.  It  may  be 
obtained  by  saponification  of  croton-oil,  or,  better,  by  the  action  of  potas- 
sium hydrate  upon  allyl  cyanide: 

C3HB,CN  +  KHO  +  HaO  =  C4H6O,OK  +  NH, 

Allyl  cyanide.        Potassium        Water.  Potassium  Ammonia, 

hydrate.  crotonate. 

It  is  an  oily  liquid;  solidifies  at  — 5°;  acrid  in  taste;  gives  off  highly 
irritating  vapors  at  temperatures  slightly  above  0°.  When  taken  inter- 
nally it  acts  as  an  irritant  poison. 

An  acid  obtained  by  oxidation  of  crotonic  aldehyde  is  probably  an  iso- 
mere,  as  it  is  in  the  form  of  crystals  at  ordinary  temperatures,  and  only 
fuses  at  73°. 

Crotonic  acid  forms  well-defined  salts,  and  products  of  substitution 
with  chlorine  and  bromine. 

r*  TT  r\  \ 

Crotonic  aldehyde,     4    Yj  [•  . — If  aldehyde,  water,  and  hydrochloric 

acid  be  mixed  together  at  a  low  temperature,  and  the  mixture  exposed  to 
diffused  daylight  for  some  days,  an  oily  liquid  is  formed,  which,  after  puri- 
fication, has  the  composition  04H8O2.  This  substance,  known  as  aldol, 
when  exposed  to  heat,  is  decomposed  into  water  and  crotonic  aldehyde: 

O.H.O.    =    H.O    +    C,H,0 

Aldol.  Water.        Crotonic  aldehyde. 

Crotonic  aldehyde  is  a  colorless  liquid;  boils  at  105°;  gives  off  highly 
irritating  vapors.  It  is  only  of  interest  as  bearing  the  same  relation  to 
croton  chloral  that  aldehyde  does  to  chloral. 

Croton  chloral — Trichlorocroton  aldehyde —  ^*  ^g  |  —  a  sub- 
stance which  has  been  recently  introduced  into  medicine  as  an  anaesthetic 
whose  action  is  particularly  directed  to  the  sensory  nerves  distributed  to 
the  head  and  face.  It  is  prepared  by  directing  a  current  of  chlorine 
through  acetic  aldehyde  as  ordinary  chloral  is  obtained  by  the  action  of 
chlorine  upon  ethylic  alcohol  (see  p.  201).  The  first  action  of  the  chlorine 
is  to  convert  ethylic  aldehyde  into  crotonic  aldehyde  by  condensation  and 
elimination  of  water;  in  the  second  stage  of  the  reaction  the  substitution 
of  three  atoms  of  chlorine  for  an  equal  number  of  atoms  of  hydrogen  in 
the  croton  aldehyde  thus  formed  takes  place. 

Angelic  acid,  CbH^  j.  O— exists  in  angelica  root,  Angelica  (U.  S.), 

in  the  flowers  of  chamomile,  Anthemis  (U.  S.),  and  in  croton-oil. 

It  crystallizes  in  colorless  prisms,  which  fuse  at  45.5°;  boils  at  185°; 

15 


226  GENERAL    MEDICAL    CHEMISTRY. 

has  an  aromatic  odor  and  an  acid,  pungent  taste;  sparingly  soluble  in  cold 
water;  readily  soluble  in  hot  water,  alcohol,  and  ether.  By  the  action  of  heat 

it  is  converted  into  its  isomere,  methylcrotonic  acid,     4     4  ^       3Yr  [•  O. 

The  JEssence  ofchamomile,  Oleum  anthimidis  (Br.),  is  a  mixture  in  vary- 
ing proportions  of  compound  ethers,  in  which  amyl  and  butyl  angelates 
predominate. 

P   TT   O  ) 
Oleic  acid,     16    3Yr  [•  O — exists  as  its  glycerin  ether,  olein,  in  most, 

if  nolfc  in  all,  the  fats  and  in  all  fixed  oils.  It  is  obtained  in  an  impure 
form  on  a  large  scale,  industrially,  as  a  by-product  in  the  manufacture  of 
candles.  This  product  is,  however,  very  impure;  to  purify  it,  it  is  first  cooled 
to  zero,  the  liquid  portion  collected,  cooled  to  — 10°,  expressed,  and  the 
solid  portion  collected;  this  is  melted  and  treated  with  half  its  weight  of 
massicot;  the  lead  oleate  so  obtained  is  dissolved  out  by  ether;  the  de- 
canted ethereal  solution  is  shaken  with  hydrochloric  acid,  the  ethereal 
layer  decanted  and  evaporated,  when  it  leaves  oleic  acid,  contaminated 
with  a  small  quantity  of  oxyoleic  acid,  from  which  it  can  be  purified  only 
by  a  tedious  process. 

Pure  oleic  acid  is  a  white,  pearly,  crystalline  solid,  which  fuses  to  a 
colorless  liquid  at  14°;  when  cold  liquid  oleic  acid  is  warmed,  it  solidifies 
at  4°;  it  is  odorless  and  tasteless;  soluble  in  alcohol,  ether,  and  cold  sul- 
phuric acid;  insoluble  in  water;  sp.  gr.  0.808  at  19°;  neutral  in  reaction. 
It  can  be  distilled  in"  vacuo  without  decomposition,  but  when  heated  in 
contact  with  air  it  is  decomposed  with  formation  of  hydrocarbons,  vola- 
tile fatty  acids,  and  sebacic  acid.  It  dissolves  the  fatty  acids  readily, 
forming  mixtures  whose  consistency  varies  with  the  proportions  of 
liquid  and  solid  acid  which  they  contain.  The  solid  acid  is  but  little 
altered  by  exposure  to  air,  but  when  liquid  it  absorbs  oxygen  rapidly, 
becomes  yellow,  rancid,  acid  in  reaction,  and  incapable  of  solidifying 
when  cooled;  these  changes  take  place  the  more  rapidly  the  higher  the 
temperature. 

Chlorine  and  bromine  attack  oleic  acid  with  formation  of  products  of 
substitution.  If  oleic  acid  be  heated  with  an  excess  of  caustic  potassa  to 
200°,  it  is  decomposed  into  palmitic  and  acetic  acids: 

O..H..O.  +  2KHO  =  C,6H3,0,K  +  C,HSO,K  +  H, 

Oleic  acid.  Potassium  Potassium  Potassium 

hydrate.  palmitate.  acetate. 

A  reaction  which  is  utilized  industrially  to  obtain  hard  soaps,  palmitates, 
form  olein,  which  itself  only  forms  soft  soaps.  Cold  sulphuric  acid  dis- 
solves oleic  acid,  and  deposits  it  unaltered  on  the  addition  of  water;  but 
if  the  acid  solution  be  heated  it  turns  brown  and  gives  off  sulphur  dioxide. 
Nitric  acid  oxidizes  it  energetically  with  formation  of  a  number  of  vola- 
tile fatty  acids  and  acids  of  another  series — suberic,  adipic,  etc.  The 
oleates  of  the  alkaline  metals  are  soft,  soluble  soaps;  those  of  the  earthy 
metals  are  insoluble  in  water,  but  soluble  in  alcohol  and  in  ether. 

Elaidic  acid  is  an  isomere  of  oleic  acid,  produced  by  the  action  upon 
it  of  nitrous  acid  in  the  preparation  of  Unguentum  hydrargyri  nitratis  (U. 
S.,  Br.).  The  nitrous  fumes  formed  convert  the  oleic  acid  contained  in 
the  oil  and  lard  used  into  elaidic  acid,  which  exists  in  the  ointment  in 
combination  with  mercury. 


SECOND    SERIES    OF    HYDRO  CARBONS OLEFINES.  227 


POLYATOMIC  COMPOUNDS. 

The  organic  compounds  hitherto  considered  may  be  looked  upon  as 
compounds  of  univalent  carbon  radicals,  these  radicals  existing  in  the 
alcohols  and  acids  in  combination  with  an  atom  each  of  oxygen  and 
hydrogen;  they  are  called  monoatomic  because  they  contain  a  single 
atom  of  hydrogen  capable  of  being  replaced  by  an  alcoholic  radical. 
There  exist  other  carbon  compounds,  in  which  the  radicals,  containing  a 
less  number  of  hydrogen  atoms  as  compared  with  the  number  of  carbon 
atoms,  have  a  valence  greater  than  one;  these  radicals  form  acids,  alcohols, 
etc.,  in  which  the  number  of  atoms  of  replaceable  hydrogen  is  greater 
than  one,  and  which  are  designated  as  polyatomic. 


NON-SATURATED  HYDROCARBONS. 

Besides  the  compounds  of  carbon  and  hydrogen  described  on  pp.  149- 
157,  in  which  all  the  valences  of  the  carbon  atoms  are  satisfied  either  by 
the  attachment  of  hydrogen  atoms,  or  by  the  interchange  of  a  single 
valence  between  neighboring  carbon  atoms,  there  exist  many  others  in 
which  the  proportion  of  hydrogen  to  carbon  is  less.  These  compounds 
are  non-saturated  in  this,  that  they  are  capable  of  uniting  directly  with 
atoms  of  other  elements,  or  with  radicals,  to  form  products  of  addition, 
while  the  composition  of  the  saturated  hydrocarbons  can  only  be  modified 
by  substitution  •  they  are  not,  however,  to  be  considered  as  containing 
any  unsatisfied  valence. 

These  hydrocarbons  are  very  numerous,  and  may  be  arranged  in  ho- 
mologous series,  as  shown  in  the  following  table  (p.  228),  each  succeeding 
series  containing  a  less  amount  of  hydrogen  in  proportion  to  the  carbon: 

Each  series  arid  its  derivatives  will  be  considered  in  the  order  given 
in  the  table. 


SECOND  SERIES  OP  HYDROCARBONS— OLEFINES. 

SERIES  C^H^. 

The  terms  of  this  series  contain  two  atoms  of  hydrogen  less  than  the 
corresponding  terms  of  the  first  series;  they  differ  in  constitution  in  this, 
that,  while  in  the  first  series  a  single  valence  is  exchanged  between  each 
two  neighboring  carbon  atoms,  in  the  second  series  two  valences  are 
exchanged  between  two  of  the  carbon  atoms: 

C  A!H 

(-  n 

C  =  H,  0  =  H, 

Propane.  Propylene. 

They  are  designated  as  olefines,  a  name  derived  from  a  property  of  the 
second  in  the  series,  which  was  formerly  known  as  olefiant  gas;  or,  to  dis- 


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SECOND    SERIES    OF    HYDROCARBONS OLEFINES.  229 

tinguish  them  from  the  terms  of  the  first  series,  by  the  terminations  ylene  or 
cne,  thus,  the  second  is  called  ethylene  or  ethane.  They  behave  as  divalent 
radicals. 

Methene — Methylene — CH2 — is  of  doubtful  existence,  known  only 
in  combination.  Ethene — Ethylene —  Olefiant  gas — Elayl — Heavy  car- 

CH, 
buretted  hydrogen —  ||      — is  formed  by  the  dry  distillation  of  fats,  resins, 

OH, 

wood,  and  coal,  and  is  one  of  the  most  important  constituents  of  illumina- 
ting gas.  It  is  also  obtained  by  the  dehydration  of  alcohol  or  ether. 

It  has  been  obtained  synthetically  in  three  ways:  1st,  by  passing  a  mix- 
ture of  hydrogen  sulphide  and  carbon  monoxide  over  iron  or  copper  heated 
to  redness;  2d,  by  heating  acetylene  in  the  presence  of  hydrogen,  or  by 
the  action  of  nascent  hydrogen  upon  copper  acetylide;  3d,  by  the  action 
of  hydrogen  upon  the  chloride  CaCl4,  obtained  by  the  action  of  chlorine 
upon  carbon  disulphide. 

It  is  prepared  in  the  laboratory  by  the  dehydration  of  alcohol  by  sul- 
phuric acid:  a  mixture  of  four  parts  by  weight  of  sulphuric  acid  and  one 
part  of  alcohol  is  placed  in  a  flask  containing  enough  sand  to  form  a  thin 
paste,  and  gradually  heated  to  about  170°;  the  gas,  which  is  given  off  in 
abundance,  is  purified  by  causing  it  to  pass  through  wash-bottles  con- 
taining water,  an  alkaline  solution,  and  concentrated  sulphuric  acid,  and 
may  be  collected  over  water. 

Pure  ethylene  is  a  colorless  gas;  tasteless;  has  a  faint  odor  resembling 
that  of  salt  water,  or  an  ethereal  odor  when  impure;  irrespirable;  spar- 
ingly soluble  in  water,  more  soluble  in  alcohol.  It  burns  with  a  luminous, 
white  flame,  and  forms  explosive  mixtures  with  air  and  oxygen.  When 
heated  for  some  time  at  a  dull  red  heat  it  is  converted  into  acetylene, 
ethyl  and  methyl  hydrides,  a  tarry  product,  and  carbon. 

Ethylene  readily  enters  into  combination.  It  unites  with  hydrogen 
to  form  ethyl  hydride,  C2H6.  With  oxygen  it  unites  explosively  on  the 
approach  of  a  flame,  with  formation  of  carbon  dioxide  and  water.  Oxidiz- 
ing agents,  such  as  potassium  permanganate  in  alkaline  solution,  convert 
it  into  oxalic  acid  and  water.  A  mixture  of  chlorine  and  etlieno,  in  the 
proportion  of  two  volumes  of  the  former  to  one  of  the  latter,  unite  with 
an  explosion  on  contact  with  flame,  the  union  being  attended  with  a 
copious  deposition  of  carbon  and  the  formation  of  hydrochloric  acid. 
Chlorine  and  ethene,  mixed  in  equal  volumes  and  exposed  to  diffused  day- 
light, unite  slowly,  with  formation  of  an  oily  liquid;  ethene  chloride,  C, 
H4C1, ;  Dutch  liquid,  to  whose  formation  ethene  owes  the  name  olefi- 
ant  gas.  By  suitable  means  ethene  may  also  be  made  to  yield  chlorinated 

groducts  of  substitution,  the  highest  of  which  is  carbon  tetrachloride,  C, 
14.  Bromine  and  iodine  also  form  products  of  addition  and  of  substitu- 
tion with  ethene.  By  union  with  (OH)2  it  forms  glycol  (q.  v.).  It  slowly 
dissolves  in  ordinary  sulphuric  acid,  with  formation  of  sulphovinic  acid; 
with  fuming  sulphuric  acid  it  combines  with  elevation  of  temperature  and 
formation  of  ethionic  anhydride. 

When  inhaled,  diluted  with  air,  ethene  produces  effects  somewhat 
similar  to  those  of  nitrous  oxide. 

The  higher  terms  of  this  series  are  of  theoretical  interest  only,  except 
the  fifth. 

Pentene — Amylene  or  valerine — C6H10 — a  colorless,  mobile  liquid, 
boiling  at  39°;  obtained  by  heating  amylic  alcohol  with  a  concentrated 
solution  of  zinc  chloride.  Its  use  as  an  anaesthetic  has  been  suggested. 


230  GENERAL    MEDICAL    C1IEMISTKY. 

CH.C1 


Ethene  chloride — Bichloride  of  ethylene — Dutch  liquid —  ! 

(JH2C1 

is  obtained  by  passing  a  current  of  ethene  through  a  retort  in  which 
chlorine  is  being  generated  and  connected  with  a  cooled  receiver.  The 
distillate  is  washed  with  a  solution  of  caustic  potassa,  afterward  with 
water,  and  is  finally  rectified.  '•;  , 

It  is  a  colorless,  oily  liquid,  which  boils  at  82.5°;  has  a  sweetish  taste 
and  an  ethereal  odor.     It  is  isomeric,  but  not  identical  with  the  chloride  of 

CaH4Cl 
xnonochlorinated    ethyl,  I  ,  which  boils  at  G4°.     It  is  capable  of  fixing 

other  atoms  of  chlorine  by  substitution  for  hydrogen,  and  thus  forming  a 
series  of  chlorinated  derivatives,  the  highest  of  which  is  CaCl,. 


DIATOMIC   ALCOHOLS. 

SERIES  CJIan+2O,. 

These  substances,  which  are  of  great  theoretical  interest,  were  discov- 
ered in  1856  by  Wurtz,  and  are  usually  designated  as  glycols.  They  are 
the  hydrates  of  the  hydrocarbons  of  the  series  CMHam,  and  consist  of  those 
hydrocarbons,  playing  the  part  of  divalent  radicals,  united  with  two  groups 


see11 


OH;  their  general  typical  formula  is  then  (CnHSn)''  )  Q       \\r    \ 

H2  )      2* 

(p.  150)  that  the  primary  monoatomic  alcohols  contain  the  group  of 
atoms  (CH2OH)'  united  with  n(CwH2n+1);  the  primary  g-lycols  are  simi- 
larly constructed,  and  consist  of  twice  the  group  (CH9OH),  united  in  the 
higher  terms  to  n(CnHan).  The  constitution  of  the  glycols  and  their  re- 
lations to  the  monoatomic  alcohols  is  indicated  by  the  following  formulae: 

CH,OH  CHaOH 

OH, 
CH,  CH2OH 

Primary  propyl  acohoL  Primary  propyl  glyooL 

As  the  monoatomic  alcohols  are  such  by  containing  in  their  molecules 
a  group  (OH),  closely  attached  to  an  electro-positive  group,  and  capable 
of  removal  and  replacement  by  an  electro-negative  group  or  atom,  so  the 
glycols  are  diatomic  by  the  fact  that  they  contain  two  such  groups  (OH); 
as  the  monoatomic  alcohols  are  therefor  only  capable  of  forming  a  single 
ether  with  a  monobasic  acid,  the  glycols  are  capable  of  forming  two  such 
ethers : 


CH,(C,H,0,)'  CH,(C,H,0,)' 

CH,  CH,OH  CH,  (CSH,0,)' 

Ethyl  acetate.  Monoacetic  glycoL  Diacetic  glycol. 


DIATOMIC    ALCOHOLS.  231 

For  the  products  of  oxidation  of  the  glycols,  see  p.  232  et  sea. 

CII2OH 
Ethene  gly  col — Etliylene  glycol  or  Alcohol  or  Hydrate —  I  . — 

CH2OH 

This,  the  best  known  of  the  glycols,  was  first  obtained  by  Wurtz.     It 
is  prepared  by  the  action  of  dry  silver  acetate  upon  ethylene  bromide: 

C2H4,Br,     +     2C2H302Ag     =     2AgBr     +     (CsHfOs),C,H4 

Bthylene  bromide.  Silver  acetate.  Silver  bromide.  Diacetic  glyool. 

The  ether  so  obtained  is  purified  by  redistillation,  and  decomposed  by 
heating  for  some  time  with  barium  hydrate: 


(C.H.O.J.C.H,     +     BaO,H.     =     (C,H,0.).Ba     + 

Diacetic  glycoL  Barium  hydrate.  Barium  acetate.  Glycol. 

It  is  a  colorless,  slightly  viscous  liquid;  odorless;  faintly  sweet;  sp. 
gr.  1.125  at  0°;  boils  at  197°;  sparingly  soluble  in  ether;  very  soluble  in 
water  and  in  alcohol. 

It  is  not  oxidized  by  simple  exposure  to  air,  but  on  contact  with  pla- 
tinum black  it  is  oxidized  to  glycolic  acid;  more  energetic  oxidants 
transform  it  into  oxalic  acid.  Chlorine  acts  slowly  upon  glycol  in  the 
cold;  more  rapidly  under  the  influence  of  heat,  producing  chlorinated 
and  other  derivatives.  By  the  action  of  dry  hydrochloric  acid  upon 
cooled  glycol,  a  product  is  formed  intermediate  between  it  and  ethylene 
chloride,  a  neutral  compound — ethene  chlorhydrate  or  ethene  chlorhydrin, 
CH2OH 

,  which  boils  at  130°. 
CH2C1 

Ethene  oxide — Ethylene  oxide — (C2H4)"O. — This  substance,  isomeric 
with  aldehyde,  is  obtained  by  the  action  of  potassium  hydrate  upon  ethene 
chlorhydrate,  mentioned  above. 

It  is  a  transparent,  volatile  liquid;  boils  at  13.5°;  gives  off  inflamma- 
ble vapors;  mixes  with  water  in  all  proportions.  It  is  capable  of  uniting 
directly  with  water  to  form  glycol;  and  with  hydrochloric  acid  gas  to 
regenerate  ethene  chlorhydrate. 

The  superior  homologues  of  ethene  glycol  and  of  ethene  oxide  are  only 
of  interest  from  a  theoretical  point  of  view. 

Taurine,  SO3C2HTN — is  isomeric  with  a  derivative  of  glycol,  isethi- 
onamide.  It  is  obtained  from  ox-bile  by  boiling  with  dilute  hydrochlo- 
ric acid;  decanting  and  concentrating  the  liquid;  separating  from  the 
sodium  chloride  which  crystallizes;  evaporating  further,  and  precipitating 
with  alcohol.  The  deposit  is  purified  by  recrystallization  from  alcohol. 

It  crystallizes  in  large,  transparent,  oblique,  rhombic  prisms,  permanent 
in  air,  quite  soluble  in  water,  almost  insoluble  in  absolute  alcohol  and 
ether. 

Taurine  has  acid  properties  and  forms  salts;  it  is  not  attacked  by  sul- 
phuric, nitric  or  nitromuriatic  acid,  but  is  oxidized  by  nitrous  acid,  with 
formation  of  water,  nitrogen,  and  isethionic  acid. 

It  exists  in  the  animal  economy,  in  the  bile  in  taurocholic  acid  (q.  v.)  ; 
and  has  also  been  detected  in  the  intestine  and  fasces,  muscle,  blood,  liver, 
kidneys,  and  lungs;  the  pneumic  acid,  described  as  existing  in  the  lung, 
is  taurine.  When  taken  internally,  it  is  eliminated  by  the  urine,  not  in  its 
own  form,  but  as  taurocarbamic  or  isethionuric  acid,  CaII8NaSO6. 


232  GENERAL    MEDICAL    CHEMISTRY. 


ACIDS  DERIVED  FROM  THE  GLYCOLS. 

As  the  acids  of  the  acetic  series  are  obtained  from  the  primary  mono- 
atomic  alcohols  by  the  substitution  of  O  for  H  in  the  characterizing 
group  CHaOH: 

CH8  CH, 

CH2,OH  CO,OH 

Ethyl  alcohol.  Acetic  acid. 

so  the  diatomic  alcohols  may,  by  oxidation,  be  made  to  yield  acids,  formed 
by  the  same  substitution  of  O  for  H3.  But  the  glycols  differ  from  the 
monoatornic  alcohols  in  containing  two  groups  CHaOH,  and  they  conse- 
quently yield  two  acids,  as  the  substitution  occurs  in  one  or  both  of  the 
alcoholic  groups: 

CH2,OH         CH2,OH         CO,OH 
CHa,OH         CO,OH          CO,OH 

Ethene  glycoL  Glycolic  acid.  Oxalic  acid. 

A  study  of  these  two  acids  shows  them  to  be  possessed  of  peculiar 
differences  of  function.  Each  of  them  contains  two  groups  (OH),  whose 
hydrogen  is  capable  of  replacement  by  an  acid  or  alcoholic  radical: 


CHa,OCaH6 
COOH 

Ethylglycolic  acid. 

CH2,OH 
CO,OC2H5 

Ethyl  glycolate. 

CHaOC2H5 
CO,OC2H& 

Ethyl  ethylglycolate. 

CO,OH 
1 
CO,0'C2H5 

Ethyloxalic  acid. 

CO,OC2HS 
CO,OC2H6 

Ethyl  oxalate. 

They  are,  therefor,  both  said  to  be  diatomic.  The  ability,  however,  of 
the  two  acids  to  form  salts  is  not  the  same,  for  while  oxalic  acid  is  capable 
of  forming  two  salts  of  univalent  metals,  and  a  salt  of  a  divalent  metal 
with  a  single  molecule  of  the  acid;  glycolic  acid  only  forms  a  single  salt  of  an 
univalent  metal,  and  two  of  its  molecules  are  required  to  form  a  salt  of  a 
divalent  metal;  in  other  words,  glycolic  acid  is  monobasic  while  oxalic  acid 
is  dibasic.  It  is  only  that  atom  of  hydrogen  which  is  contained  in  the  elec- 
tro-negative group  COOH,  which  is  replaceable  as  acid  hydrogen,  while 
that  of  the  electro-positive  group  CH2OH  is  only  replaceable,  as  is  the 
corresponding  hydrogen  of  an  alcohol. 

In  general  terms,  therefor,  the  atomicity  of  an  organic  acid  may  be 
greater  than  its  basicity,  the  former  representing  the  number  of  hydrogen 
atoms  contained  in  its  molecule,  which  are  capable  of  being  displaced  by 
alcoholic  radicals,  while  the  latter  represents  the  number  of  hydrogen 
atoms  replaceable  by  electro-positive  elements  or  radicals,  with  formation 
of  salts  or  of  ethers. 

There  may,  therefor,  be  obtained  from  the  glycols,  by  more  or  less  com- 
plete oxidation,  two  series  of  acids;  those  of  the  first  are  diatomic  and 
monobasic;  those  of  the  second  diatomic  and  dibasic. 


DIATOMIC    AND    MONOBASIC    ACIDS.  233 

DIATOMIC  AND  MONOBASIC  ACIDS. 

SERIES  CnH2B03. 
The  acids  of  this  series  at  present  known  are: 


Butylactic  acid.  .C4O3H8 
Oxy  valeric  acid .  CsOsH!  0 


Leucic  acid C6O3Hu 

(?)CEnanthic  acid.Ci4O2H28 


(Carbonic  acid) COaH, 

Glycolic  acid CQO3H4 

Ethyleno-lactic  acid  ..C3O3H« 

The  first-named  of  these  acids,  although  not  capable,  so  far  as  yet 
known,  of  existing  in  the  free  state,  is  widely  represented  in  nature  in 
the  shape  of  its  salts,  the  carbonates.  Its  position  in  this  series  is  an 
anomaly,  and  at  first  sight  a  contradiction,  as  it  is  certainly  not  a  mono- 
basic, but  a  distinctly  dibasic  acid,  or,  more  properly  speaking,  would  be 
such  were  it  obtained  in  a  state  of  purity;  it  is,  however,  in  this  position 
as  the  inferior  homologue  of  glycolic  acid  that  carbonic  acid  is  most 
naturally  placed,  and  the  dibasic  nature  of  the  latter  acid  does  not  pre- 
sent any  valid  objection  to  such  a  position,  for  if  we  consider  one  term  of 
a  series  as  derivable  from  its  superior  homologue  by  the  subtraction  of 
CH2,  and  if  we  bear  in  mind  that  the  basic  nature  of  the  hydrogen  atom 
in  a  group  OH  depends  upon  its  close  union  with  the  group  CO  (or  with 
some  other  electro-negative  group),  it  will  become  evident  that  the  inferior 
homologue  of  glycolic  acid  must  contain  two  groups  OH  united  to  one 
CO,  and  must,  therefor,  be  dibasic: 


CHaOH  OH 

—  CH.     =  or  \^v/c    /-\TT 

)O,OH  CO,OH 

Glycolic  acid.  Carbonic  acid. 


i, 


The  other  acids  of  the  series  are  formed:  First. — By  the  partial  oxida- 
tion of  the  corresponding  glycol: 

CHaOH  CHaOH 

I  +     Oa     =       |  +      T> 

CHaOH  CO,OH 

Glycol.  Glycolic  acid.  Water. 

Second. — By  the  combined  action  of  water  and  silver  oxide  upon  the 
monochlor-acid  of  the  acetic  series,  or  by  heating  the  alkaline  salt  of 
such  an  acid  with  water  or  potassium  hydrate: 

CHaCl  CH3OH 


4-  f>0      =                      +     KOI 

COOK  CO,OH 

Potassium  Water.                     Glycolic  acid.            Potassium 

monochloracetate.  chloride. 

Third. — By  reducing  the  corresponding  acid  of  the  oxalic  series  by 
.nascent  hydrogen: 

COOH  CHaOH 

COOH  COOH 

Oxalic  acid.  Glycolic  acid.                  Water. 


234  GENERAL    MEDICAL    CHEMISTRY. 


Carbonic  Acid, 

Although  this  acid  has  not  been  isolated,  it  is  probable  that  it  exists 
in  aqueous  solutions  of  carbon  dioxide,  which  have  an  acid  reaction,  while 
the  dry  oxide  is  neutral  to  test-paper.  Its  salts,  the  carbonates,  are 

widely  distributed  in  nature,  and  have  th£  general  composition  CO/  Q^T 

m/OM' 

'°\OM',  or 


Oxides  of  Carbon. 

These  are  two  in  number: 

Carbon  monoxide CO 

Carbon  dioxide COa 

Carbon  Monoxide. 

Carbonic  oxide — Carbonous  oxide — CO — was  discovered  in  1799,  by 
Priestley.  It  does  not  exist  in  nature,  but  is  formed  whenever  carbon  is 
burned  with  a  supply  of  air  insufficient  to  the  formation  of  carbon  dioxide; 
when  carbon  dioxide  is  partially  reduced  by  passage  over  red-hot  char- 
coal, iron,  zinc,  etc.,  and  when  vapor  of  water  is  decomposed  by  coal 
heated  to  bright  redness. 

When  required  in  the  laboratory,  it  is  obtained  either:  lst,Jby  passing 
dry  carbon  dioxide  over  red-hot  charcoal;  or,  2d,  by  heating  together 
oxalic  and  sulphuric  acids: 

C204HQ     +     S04H3     =     S04H2     +     H20     +     CO     +     CO2 

Oxalic  acid.  Sulphuric  Sulphuric  Water.  Carbon  Carbon 

acid.  acid.  monoxide.  dioxide. 

The  resulting  gas  is  passed  through  wash-bottles  containing  lime-water, 
which  retains  the  dioxide. 

It  is  a  colorless,  odorless,  tasteless  gas;  has  been  recently  liquefied  by 
Cailletet;  sp.  gr.  0.9678 — A,  14  H;  very  sparingly  soluble  in  water  and 
in  alcohol,  its  solubility  in  the  latter  fluid  being  remarkable  for  not  vary- 
ing between  0°  and  20°. 

It  burns  in  air  with  formation  of  carbon  dioxide  and  with  a  blue 
flame;  its  mixtures  with  air  and  oxygen  are  explosive  on  contact  with 
flame  if  the  proportion  be  not  too  far  removed  from  CO:O;  it  is  also 
oxidized  toCO2  in  the  cold  by  chromic  acid.  The  most  valuable  property 
of  carbon  monoxide  is  its  power  of  reducing  many  metallic  oxides  at  a  red 
heat,  a  property  which  is  largely  utilized  in  metallurgy.  It  is  rapidly  ab- 
sorbed by  ammoniacal  solutions  of  the  cuprous  salts,  a  property  utilized  in 
gas-analysis;  it  is  also  absorbed  by  hot  potassium  hydrate  solution,  with 
formation  of  potassium  formiate.  Being  a  non-saturated  compound,  it 
readily  unites  directly  with  other  elements,  as  with  oxygen,  to  form  COa 


CARBOX    MONOXIDE.  235 

and  with  chlorine  to  form   COC12,  the  latter  a  colorless,  suffocating  gas, 
known  as  phosgene,  or  carbonyl  chloride. 

Toxicology. — Carbon  monoxide  is  an  exceedingly  poisonous  gas,  and 
is  the  chief  toxic  constituent  of  the  gases  given  off  from  blast-furnaces, 
from  defective  flues,  and  open  coal  or  charcoal  fires,  and  of  illuminating 
gas.  An  atmosphere  containing  but  a  small  proportion  of  this  gas  pro- 
duces asphyxia  and  death,  even  if  the  quantity  of  oxygen  present  be  equal 
to  or  even  greater  than  that  normally  existing  in  the  atmosphere;  0.5 
per  cent,  of  carbon  monoxide  in  air  is  sufficient  to  kill  a  small  bird  in  a 
few  moments,  and  one  per  cent,  proves  fatal  to  small  mammals. 

Poisoning  by  carbon  monoxide  may  occur  in  several  ways.  By  inha- 
lation of  the  gases  discharged  from  blast-furnaces  and  from  copper-fur- 
naces, the  former  containing  twenty-five  to  thirty-two  per  cent.,  and  the 
latter  thirteen  to  nineteen  per  cent,  of  carbon  monoxide.  By  the  fumes 
given  off  from  charcoal  burned  in  a  confined  space — a  favorite  means  of 
suicide,  especially  in  France — the  gas  produced  by  this  combustion  is  chiefly 
a  mixture  of  the  two  oxides  of  carbon,  the  dioxide  predominating  largely, 
especially  when  the  combustion  is  most  active.  The  following  is  given 
by  Leblanc  as  the  composition  of  an  atmosphere  produced  by  burning 
charcoal  in  a  confined  space,  and  which  proved  rapidly  fatal  to  a  dog: 
oxygen,  19.19;  nitrogen,  76.62;  carbon  dioxide,  4.61;  carbon  monoxide, 
0.54;  marsh-gas,  0.04.  Obviously  the  deleterious  effects  of  charcoal-fumes 
are  more  rapidly  fatal  in  proportion  as  the  combustion  is  imperfect  and 
the  room  small  and  ill-ventilated. 

A  fruitful  source  of  carbon  monoxide  poisoning3  sometimes  fatal,  but 
more  frequently  producing  languor,  headache,  and  debility,  is  to  be  found 
in  the  stoves,  furnaces,  etc.,  used  in  heating  our  dwellings  and  other 
buildings,  especially  when  the  fuel  is  anthracite  coal.  This  fuel  produces 
in  its  combustion,  when  the  air-supply  is  not  abundant,  considerable  quan- 
tities of  carbon  monoxide,  to  which  a  further  addition  may  be  made  by  a 
reduction  of  the  dioxide,  also  formed,  in  passing  over  red-hot  iron;  this 
poisonous  gas  may  find  its  way  into  the  rooms  either  through  cracks  or 
other  defects  in  the  stoves,  flues,  or  pipes;  by  occasional  downward  cur- 
rents of  air  passing  over  fires  in  open  fireplaces,  or,  much  more  frequently, 
by  direct  passage  through  the  heated  metal.  Experiment  has  shown  that 
metals,  notably  cast-iron,  are  quite  pervious  to  gases  when  heated  to  red- 
ness; when,  therefor,  a  stove  or  the  fire-box  of  a  hot-air  furnace  becomes 
red-hot,  a  portion  of  the  gases  formed,  by  the  combustion  of  the  fuel 
passes  through  the  pores  of  the  metal  to  contaminate  the  air  without,  and 
give  rise  to  carbonic  oxide  poisoning  to  a  degree  depending  upon  the  de- 
gree of  imperfection  of  the  ventilation,  the  nature  of  the  fuel,  and  the 
amount  of  air  supplied  to  it.  The  obvious  precautions  required  to  avoid 
this  form  of  what  may  be  called  chronic  carbonic  oxide  poisoning,  and 
which  is  by  no  means  uncommon,  are:  1st,  to  have  the  stoves  or  furnaces 
lined  with  fire-clay,  which  tends  to  prevent  their  overheating  and  to  di- 
minish their  perviousness  to  gases;  2d,  to  avoid  heating  to  redness;  3d, 
to  furnish  an  abundant  supply  of  air  to  the  fuel;  4th,  to  secure  proper 
ventilation;  and  5th,  in  the  case  of  hot-air  furnaces,  to  obtain,  by  an 
abundant  supply  of  external  air  to  the  air-chamber,  a  large  supply  of  mod- 
erately heated  air  rather  than  a  small  quantity  of  very  hot  air. 

Of  late  years  cases  of  fatal  poisoning  by  coal-gas  are  of  very  frequent 
occurrence,  caused  either  by  accidental  inhalation,  by  inexperienced  per- 
sons blowing  out  the  gas,  or  by  suicides.  There  can  be  little  doubt  that 
the  most  actively  poisonous  ingredient  of  coal-gas  is  carboa  monoxide, 


236  GENERAL    MEDICAL    CHEMISTRY. 

which  exists  in  the  ordinary  illuminating  gas  in  the  proportion  of  4  to 
7.5  per  cent.,  and  in  water-gas,  made  by  decomposing  superheated  steam 
by  passage  over  red-hot  coke,  and  subsequent  charging  with  vapor  of  hy- 
drocarbons, in  the  large  proportion  of  thirty  to  thirty-five  per  cent. 

The  method  in  which  carbon  monoxide  produces  its  fatal  effects  is  by 
forming  with  the  blood-coloring  matter  a  compound  which  is  more  stable 
than  oxyhaemoglobin,  and  thus  causing  asphyxia  by  destroying  the  power 
of  the  blood-corpuscles  of  carrying  oxygen  from  the  air  to  the  tissues. 
This  compound  of  carbonic  oxide  and  hemoglobin  is  quite  stable,  and 
hence  the  symptoms  of  this  form  of  poisoning  are  very  persistent,  lasting 
until  the  place  of  the  coloring-matter  thus  rendered  useless  is  supplied  by 
new-formation.  The  prognosis  is  very  unfavorable  when  the  amount  of 
the  gas  inhaled  has  been  at  all  considerable;  the  treatment  usually  fol- 
lowed, i.  e.,  artificial  respiration,  and  inhalation  of  oxygen,  failing  to  restore 
the  altered  coloring-matter.  There  would  seem  to  be  no  form  of  poison- 
ing in  which  transfusion  of  blood  is  more  directly  indicated  than  in  that 
by  carbon  monoxide. 

Detection  after  death. — The  blood  of  those  asphyxiated  by  carbon 
monoxide  is  persistently  bright  red  in  color;  when  suitably  diluted  and 
examined  with  the  spectroscope,  it  presents  two  absorption-bands  very 
similar  to  those  of  oxyhasmoglobin  (see  p.  369),  but  more  equal  to  each 
other  in  intensity  and  slightly  nearer  the  violet  end  of  the  spectrum; 
owing,  however,  to  the  greater  stability  of  the  carbonic  oxide  compound, 
its  spectrum  may  be  readily  distinguished  from  that  of  the  oxygen  com- 
pound by  the  addition  of  a  reducing  agent  (an  ammoniacal  solution  of 
ferrous  tartrate),  which  changes  the  spectrum  of  oxyhaemoglobin  to  the 
single-band  spectrum  of  reduced  haemoglobin,  while  that  of  the  carbon 
monoxide  compound  remains  unaltered,  or  only  fades  partially. 

If  a  solution  of  caustic  soda  of  sp.  gr.  1.3  be  added  to  normal  blood, 
a  black,  slimy  mass  is  formed,  which,  when  spread  upon  a  white  plate, 
has  a  greenish  brown  color;  the  same  reagent  added  to  blood  altered  by 
carbonic  oxide  forms  a  firmly  clotted  mass,  which  in  thin  layers  upon  a 
white  surface  is  bright  red  in  color. 

For  the  method  of  detecting  and  determining  carbon  monoxide  in 
gaseous  mixtures,  see  p.  244. 


Carbon  Dioxide. 

Carbonic  anhydride — Carbonic  acid  gas — CO, — exists  in  small  pro- 
portion in  the  atmosphere,  and  in  solution  in  natural  waters.  It  is  formed 
whenever  a  substance  containing  carbon  is  burned  in  air  or  oxygen,  and 
when  a  carbonate  is  decomposed  by  a  stronger  acid. 

It  is  best  obtained  by  decomposing  a  natural  carbonate,  marble  or 
limestone,  by  a  mineral  acid — hydrochloric  acid. 

At  ordinary  temperatures  and  pressures  it  is  a  colorless  gas;  produces 
a  sense  of  suffocation  when  inhaled;  has  an  acidulous  taste;  sp.  gr.  1.529 
at  0°;  soluble  in  an  equal  volume  of  water  at  the  ordinary  pressure. 
When  subjected  to  a  pressure  of  thirty-eight  atmospheres  at  0°,  fifty 
atmospheres  at  15°,  or  seventy-three  atmospheres  at  30°,  it  is  converted 
into  a  transparent,  mobile  liquid,  by  whose  evaporation,  when  the  pres- 
sure is  relieved,  a  degree  of  cold  is  produced  sufficient  to  solidify  a  por- 
tion as  a  snow-like  mass,  which,  by  spontaneous  evaporation  in  air,  pro- 
duces a  temperature  of  — 90°. 


CARBON    DIOXIDE. 


237 


Carbon  dioxide  neither  burns  nor  does  it  support  combustion;  when 
heated  to  1,300°,  it  is  decomposed  into  carbon  monoxide  and  oxygen;  a 
similar  decomposition  is  brought  about  by  the  passage  through  it  of 
electric  sparks.  When  heated  with  hydrogen  it  yields  carbon  monoxide 
and  water;  when  potassium,  sodium,  or  magnesium  is  heated  in  an  atmos- 
phere of  carbon  dioxide,  the  gas  is  decomposed  with  formation  of  a  car- 
bonate and  separation  of  carbon.  When  caused  to  pass  through  solutions 
of  the  hydrates  of  sodium,  potassium,  calcium,  or  barium,  it  is  absorbed, 
with  formation  of  the  carbonates  of  those  elements,  which,  in  the  case  of 
the  last  two,  are  deposited  as  white  precipitates.  Solution  of  potash  is 
frequently  used  in  analysis  to  absorb  carbon  dioxide,  and  lime  and  baryta 
water  as  tests  for  its  presence.  The  hydrates  mentioned  also  absorb 
carbon  dioxide  from  moist  air. 

Atmospheric  carbon  dioxide. — Carbon  dioxide  is  a  constant  consti- 
tuent of  atmospheric  air  in  small  and  varying  quantities;  the  mean 
amount  in  free  country  air  being  about  four  parts  in  ten  thousand.  The 
variations  in  amount  under  different  conditions  is  shown  in  the  following 
table: 

AMOUNT  OP  CABBON  DIOXIDE  IN  AIR. 


Collected  at 

Parts  in  10,000. 

Determined  by 

Paris  

3.190 

Boussingault  and  Lewy. 

Andilly  —  twenty  miles  from  Paris  

2989 

Boussingault  and  Lewy. 

Paris  —  Day 

3  9 

Boussingault 

Night    

42 

Boussingault. 

5.42 

Lewy. 

Night  

3.346 

Lewy. 

Day  

3.011 

Thorpe. 

Night  

2.995 

Thorpe. 

468 

Saussure 

Meadow  —  three-fourths  mile  from  Geneva  : 

4.79  to  5.  18 

Saussure. 

3.  57  to  4.  56 

Saussure. 

3  85  to  4  25 

Saussure 

4.57 

Saussure. 

427 

Saussure. 

439 

Saussure. 

Arctic  regions  

4,83  to  6.41 

Moss. 

Gosport  barracks  

6.45 

Chaumont. 

14.04 

Chaumont 

Hilsey  Hospital  

472 

Chaumont. 

Portsmouth  Hospital  

9  76 

Chaumont. 

Cell  in  Pentonville  Prison  

989 

Chaumont. 

Cell  in  Chatham  Prison  

16.91 

Chaumont. 

Boys'  school  —  69  cubic  feet  per  bead  

31 

Roscoe. 

Room  —  51  cubic  feet  per  head     

52  8 

Weaver. 

Girls'  school  —  150  cubic  feet  per  head  

723 

Pettenkofer 

Greenhouse  —  Jardin  des  Plantes  

1.0 

Theatre—  Parquet  

23.0 

Near  ceiling  

43  0 

Lead  mine—  Lamps  burn  

80.0 

F.  Leblano. 

Lamps  extinguished  

390.0 

F.  Leblanc. 

Grotto  del  Cane  

7  360  0 

F   Leblanc. 

It  will  be  observed  that  on  land  the  amount  is  greater  by  night  than 
by  day,  while  the  reverse  is  the  case  at  sea;  on  land  the  green  parts  of 


238 


GENERAL    MEDICAL    CHEMISTRY. 


plants  absorb  carbon  dioxide  during  the  hours  of  sunlight,  but  not  during 
those  of  darkness.  The  increase  in  the  amount  in  air  over  large  bodies 
of  water  during  the  day-time  is  due  to  the  less  solubility  of  carbon  di- 
oxide in  the  surface-water  when  heated  by  the  sun's  rays.  The  absence 
of  vegetation  accounts  for  the  large  quantity  of  carbon  dioxide  in  the  air 
of  the  polar  regions,  and  the  same  cause,  aided  by  an  increased  produc- 
tion, for  its  excess  in  the  air  of  cities  over  that  of  the  country. 

The  sources  of  atmospheric -carbon  diojxide  are: 

First. — The  respiration  of  animals.— The  air  expired  from  the  lungs 
of  animals  contains  a  quantity  of  carbon  dioxide,  varying  with  the  age, 
sex,  food,  and  muscular  development  and  activity,  while,  at  the  same  time, 
a  much  smaller  quantity  is  discharged  by  the  skin  and  in  solution  in  the 
urine.  The  following  table,  from  the  experiments  of  Andral  and  Gavar- 
ret,  indicates  the  quantity  of  carbon  dioxide  eliminated  by  males  of  vari« 
ous  ages: 

ELIMINATION  OF  CAEBON  DIOXIDE. 


Age. 

Mean 
weight. 

Carbon  clim- 
inated,  in 
grams. 

Carbon  diox- 
ide elimina- 
ted, in  grams 

Oxygen   a  b  - 
sorbed,     in 
grams. 

Carbon  diox- 
ide elimina- 
ted, in  litres. 

Oxygen    ab- 
sorbed,   in 
litres. 

In 
kilos. 

Intt)s. 

Inl 
hour. 

In  24 
hours. 

Inl 
hour. 

In  24 
hours. 

Inl 
hour. 

In  24 

hours. 

Inl 
hour. 

In  24 
hours. 

Inl 
hour. 

In  24 

honrs. 

8  years        .           

22.26 
46.41 
53.89 

60.88 
06.90 
67.15 
63.35 

49.07 
102  32 
117.70 
134.22 
147.49 
148.04 
139.66 

B.O 
8.7 
10.8 
11.4 
12.2 
10.1 
9.2 

120.8 
208.8 
259.2 
273  6 
292.8 
242.4 
220.8 

18.3 
31.9 
39.6 
41.8 
44.7 
37.0 
33.7 

442.9 
765.6 
950.4 
1003  2 
1073.  « 
888.  S 
809.6 

15.613 
27.]  66 
33.723 
35.599 
38.094 
31  .537 
28.727 

374.70 
651.98; 
809.36 
854.321 
914.  28  j 
756.89 
689.45 

9.30 
16.21 
20.13 
21.25 
22.72 
18.81 
17.13 

225.16 
389.22 
483.17 
510.01 
545  81 
451.85 
411.59 

8  63 

18.91 
23.48 
24.78 
26.52 
21.95 
20.00 

207.22 
453.89 
563.42 
594.79 
H36.47 
5-26.92 
479.98 

16  years.  ... 

18  to  20  years  

20  to  24  years. 

40  to  60  years  

60  to  80  years.  .  .  . 

In  females  the  increase  of  elimination  follows  the  same  rule  as  with 
males  until  puberty,  when  it  ceases  and  the  amount  exhaled  remains 
about  the  same  until  the  menopause,  when  the  elimination  of  carbon  di- 
oxide suddenly  increases  to  nearly  the  same  as  that  occurring  in  males  of 
the  same  age,  and  subsequently  gradually  declines  with  advancing  age. 
During  pregnancy  the  elimination  of  carbon  dioxide  is  temporarily  in- 
creased. In  both  sexes  and  at  all  ages  the  exhalation  of  carbon  dioxide 
is  greater  during  muscular  activity  than  when  the  individual  is  at  rest, 
and  greater  in  those  whose  muscular  development  is  more  perfect.  An 
adult  man  discharges  20.77  litres = three-fourths  cubic  foot  of  carbon  di- 
oxide per  hour,  or  498.88  litres=eighteen  cubic  feet  per  diem. 

The  expired  air  under  ordinary  conditions  contains  about  4.5  per  cent, 
by  volume  of  carbon  dioxide,  the  proportion  being  greater  the  slower  the 
respiration. 

Second. —  Combustion. — The  greater  part  of  the  atmospheric  carbon 
dioxide  is  a  product  of  the  oxidation  of  carbon  in  some  form  as  a  source 
of  light  and  heat.  In  the  following  table  are  given  the  amounts  of 
carbon  dioxide  produced  and  of  air  consumed  by  different  kinds  of  fuel 
and  illuminating  materials;  by  comparing  them  with  the  quantities  of  the 
same  gases  produced  and  consumed  by  an  adult  man  it  will  be  seen  that 
in  equal  times  an  ordinary  gas-burner  produces  nearly  six  times  as  much 
carbon  dioxide  and  consumes  nearly  ten  times  as  much  air  as  a  man.  The 


CARBON    DIOXIDE. 


239 


amount  of  air  consumed  by  fuels  is,  for  practical  purposes,  greater  than 
that  given  in  the  table,  as  the  oxidation  is  never  complete,  the  air  in  the 
chimney  frequently  containing  ten  per  cent,  of  oxygen  by  volume  (see 
below). 


COMBUSTION  OF  FUEL. 


Fuel. 

4 

A 

h' 
|g 

Average  per- 
centage of 

Carbon   dioxide   pro- 
duced by 

Air  deoxidized  by 

Heat  units. 

1  Light  in  standard  candles, 
1  100.  1 

Carbon. 

Hydrogen. 

One  volume  in  vol- 
umes. 

One  part  by  weight 
in  parts  by  weight. 

In  one  hour. 

One  volume  in  vol- 
umes. 

.s 

^o  . 
5  jj 

ga 

o 

26.89 

In  one  hour. 

In 

kilos. 

In 
litres. 

In 

kilos. 

In 

litres. 

100  '.6 
1UO.U 

100.0 

2.39 

34462 
8080 
2474 
2403 
13063 
11857 
11000 
11775 

Cirbon  to  CO2 

3  65 

9.83 
4.93 

42  86 

1.0 
1.0 
2.0 
0.80 

1.57 
2.75 
3.14 
1.67 
3  08 

.... 

.... 

2.39 
9.55 

14  33 

7.14 

0.44 
13.45 
12.67 
11.04 
12  07 

75.0 
85.72 
40.0 
84  0 

25.  00 

14  28 
55.0 
13.0 

Ethene 

Coal-gas  

140  litres 

0.221 

112 

1.293 

1000 

15  gr. 
10  gr. 
10  gr. 
42  gr. 

87.0 
79.2 
76.05 
70.48 

39  10 

13.0 
13.2 

12.  (a 

10.5 
4.90 

•• 

3.17 
2.89 
2.9 
2.81 

1.43 

3.10 
1.64 
3  17 

0.048 
0.029 
0.029 
0.118 

25 
15 
15 
60 

'.'.'. 

12.12 
11.24 
8.69 
8.28 

5.16 
8  36 

4.82 

0.235 
0.146 
0.112 

0.450 

182 
113 
86.9 
348 

11055 
10496 
9716 

3600 
7640 
3000 

6000 
7183 

180 
100 
84 
15U 

Wax  

Stearic  acid 

Colza-oil     

Wood  (dry  pine).  .     .  . 

Wood  charcoal       .... 

85  0 

Peat  

Coke 

45.  U 
87  0 

1.5 

8.55 
9.22 

.... 

90.0 
52.17 

2.5 

iy.04 

3  29 

Alcohol  

Adult  man 

10  gr.  C. 

•• 

1.90 

0.037 

19 

... 

8.64 

0.134 

104 

Third.  —  Fermentation.  —  Most  fermentations,  including  putrefactive 
changes,  are  attended  by  the  liberation  of  carbon  dioxide;  thus,  alcoholic 
fermentation  takes  place  according  to  the  equation: 


180 


92 


44 


and  consequently  discharges  into  the  air  forty-four  parts  by  weight  of 
carbon  dioxide  for  every  ninety-two  parts  of  alcohol  formed,  or  191.5  litres 
of  gas  for  every  litre  of  absolute  alcohol  obtained. 

Fourth. — Tellural  sources. — Volcanoes  in  activity  discharge  enormous 
quantities  of  carbon  dioxide,  and,  in  volcanic  countries,  the  same  gas  is 
thrown  out  abundantly  through  fissures  in  the  earth.  All  waters,  sweet 
and  mineral,  hold  this  gas  in  solution,  and  those  which  have  become 
charged  with  it  under  pressure  in  the  earth's  crust,  upon  being  relieved 
of  the  pressure  when  they  reach  the  surface,  discharge  the  excess  into 
the  air. 

Fifth. — Manufacturing  processes. — Large  quantities  of  carbon  dioxide 
are  added  to  the  air  in  the  vicinity  of  lime-  and  brick-kilns,  cement- 
works,  etc. 


240  GENERAL    MEDICAL    CHEMISTRY. 

Sixth. — In  mines,  after  explosions  of  "fire-damp."  These  explosions 
are  caused  by  the  sudden  union  of  the  carbon  and  hydrogen  of  CH4  with 
the  oxygen  of  the  air,  and  are  consequently  attended  by  the  formation 
of  large  volumes  of  carbon  dioxide,  known  to  miners  as  after-damp. 

Constancy  of  the  amount  of  atmospheric  carbon  dioxide. — It  has  been 
roughly  estimated  by  Poggendorff  that  2,500,000,000,000  cubic  metres  of 
carbonic  acid  gas  are  annually  discharged  into  our  atmosphere,  and  that 
this  quantity  represents  one  eighty-sixth-of  the  total  amount  at  present 
existing  therein.  This  being  the  case,  with  the  present  production,  the 
percentage  of  atmospheric  carbon  dioxide  would  be  doubled  in  eighty-six 
years;  no  such  increase  has,  however,  been  observed,  and  the  average 
percentage  found  by  Angus  Smith,  in  1872,  is  about  the  same  as  that  ob^ 
served  by  Boussingault  in  1840,  i.  e.,  four  parts  in  ten  thousand.  The 
carbon  dioxide  discharged  into  the  air  is,  therefor,  removed  from  it  about 
as  fast  as  it  is  produced.  This  removal  is  effected  in  two  ways:  1st,  by 
the  formation  of  deposits  of  earthy  carbonates  by  animal  organisms, 
corals,  mollusks,  etc.;  2d,  principally  by  the  process  of  nutrition  of  vege- 
tables, which  absorb  carbon  dioxide  both  by  their  roots  and  leaves,  and 
in  the  latter,  under  the  influence  of  the  sun's  rays,  decompose  it,  retain- 
ing the  carbon,  which  passes  into  more  complex  molecules;  and  discharg- 
ing a  volume  of  oxygen  about  equal  to  that  of  the  carbonic  acid  gas 
absorbed. 

Air  contaminated  with  excess  of  carbon  dioxide,  and  its  effects  upon 
the  organism. — When,  from  any  of  the  above  sources,  the  air  of  a  given 
locality  has  received  sufficient  carbon  dioxide  to  raise  the  proportion 
above  seven  parts  in  ten  thousand  by  volume,  it  is  to  be  considered  as 
contaminated;  the  seriousness  of  the  contamination  depending  not  only 
upon  the  amount  of  the  increase,  but  also  upon  the  source  of  the  carbon 
dioxide.  If  the  gas  be  derived  from  fermentation,  or  from  tellural  or 
manufacturing  sources,  it  is  simply  added  to  the  otherwise  unaltered  air, 
and  the  absolute  amount  of  oxygen  present  remains  the  same;  when,  how- 
ever, it  is  produced  in  a  confined  space  by  the  processes  of  combustion  and 
respiration,  the  composition  of  the  air  is  much  more  seriously  modified, 
as  not  only  is  there  addition  of  a  deleterious  gas,  but  a  simultaneous  re- 
moval of  an  equal  volume  of  oxygen;  hence  the  importance  of  providing, 
by  suitable  ventilation,  for  the  supply  of  new  air  from  without  to  habi- 
tations and  other  places  where  human  beings  are  collected  within  doors, 
especially  where  the  illumination  is  artificial. 

Although  an  adult  man  deoxidizes  a  little  over  one  hundred  litres  of 
air  in  an  hour,  a  calculation  of  the  quantity  which  he  would  require  in  a 
given  time  cannot  be  based  exclusively  upon  that  quantity,  as  the  deoxida- 
tion  cannot  be  carried  to  completeness;  indeed,  when  the  proportion  of  car- 
bon dioxide  in  air  exceeds  five  per  cent.,  it  becomes  incapable  of  support- 
ing life,  while  a  much  smaller  quantity,  one  per  cent.,  is  provocative  of 
severe  discomfort,  to  say  the  least. 

In  calculating  the  quantity  of  air  which  should  be  supplied  to  a  given 
enclosed  space,  most  authors  have  agreed  to  adopt  as  a  basis  that  the 
percentage  of  carbon  dioxide  should  not  be  allowed  to  exceed  0.6  volumes 
per  1,000;  of  which  0.4  are  normally  present  in  air,  and  0.2  the  product 
of  respiration  or  combustion.  Taking  the  amount  of  carbon  dioxide 
eliminated  b}*-  an  adult  at  19  litres  (  =  0.7  cubic  foot)  per  hour,  a  man  will 
have  brought  the  air  of  an  air-tight  space  of  100  cubic  metres  (=  3,500 
cubic  feet)  up  to  the  permissible  maximum  of  impurity  in  an  hour.  The 
following  table  is  given  by  Parkes  to  indicate  the  contamination,  of  air 


CARBOK    DIOXIDE. 


241 


by  the  respiration  of  an  adult  in  an  hour,  and  the  supply  of  external  air 
required  to  restore  the  proper  equilibrium: 


Amount  of  air  neces- 

Amount of  cubic  space 
(breathing-space)  for 
one    man    in    cubic 
feet. 

Ratio  per  1,000  of  COa 
from   respiration   at 
the  end  of  one  hour, 
if  there  have  been  no 
change  of  air. 

sary    to     dilute    to 
standard  of  0.2,   or 
includinginitialCOj, 
of  0.6  per  1,000  vol- 
umes during  the  first 

Amount   necessary  to 
dilute    to   the  given, 
standard   every  hour 
after  the  first. 

hour. 

100 

6.00 

2,900 

3,000 

200 

3.00 

2,800 

3,000 

300 

2.00 

2,700 

3,000 

400 

1.50 

2,600 

3,000 

500 

1.20 

2,500 

3,000 

600 

1.00 

2,400 

3,000 

700 

0.85 

2,300 

3,000 

800 

0.75 

2,200 

3,000 

900 

0.66 

2,100 

3,000 

1,000 

0.60 

2,000 

3,000 

Practically,  owing  to  the  imperfect  closing  of  doors  and  windows, 
and  to  ventilation  by  chimneys,  inhabited  spaces  are  never  hermetically 
closed,  and  a  less  quantity  of  air-supply  than  that  indicated  in  the  table 
may  usually  be  considered  as  sufficient. 

A  sleeping-room  occupied  by  a  single  person  should  have  a  cubic  space 
of  30  to  50  cubic  metres  (  =  1,050  to  1,800  cubic  feet),  conditions  which 
are  fulfilled  in  rooms  measuring  10  X  13  x  8  feet,  and  13  x  15.6  x  9  feet. 

In  calculating  the  space  of  dormitories  to  be  occupied  by  several 
healthy  people,  the  smallest  air-space  that  should,  under  any  circum- 
stances, be  allowed,  is  12  cubic  metres  (=420  cubic  feet)  for  each  person. 
To  determine  the  number  of  individuals  that  may  sleep  in  a  room,  multi- 
ply its  length,  width,  and  height  together,  and  divide  the  product  by  420 
if  the  measurement  be  in  feet,  or  by  12  if  it  be  in  metres.  Thus,  a  dor- 
mitory 40  feet  long,  20  feet  wide,  and  10  feet  high,  is  fitted  for  the  ac- 
commodation of  19  persons  at  most,  for 


40  x  20  x  10=8,000  and 


=  19.05. 


As  a  rule,  in  places  where  many  persons  are  congregated,  it  is  neces- 
sary to  resort  to  some  scheme  of  ventilation  by  which  a  sufficient  supply 
of  fresh  air  shall  be  introduced  and  the  vitiated  air  removed,  the  quantity 
to  be  supplied  varying  according  to  circumstances.  Experiment  has 
shown  that  in  order  to  keep  the  air  pure  to  the  senses  the  quantity  of  air 
which  must  be  supplied  per  head  and  per  hour  in  temperate  climates  are 
as  shown  in  table  on  following  page.  The  amounts  given  are  the  small- 
est permissible,  and  should  be  exceeded  wherever  practicable. 

Lights.  —  The  amounts  of  air  to  be  supplied  to  each  individual,  given  in 
the  last  section,  are,  with  the.  exception  of  those  furnished  in  mines,  based 
upon  the  supposition  that  coal-gas  is  not  used  as  a  means  of  artificial  il- 
lumination, or  that  the  burners  are  so  arranged  with  reference  to  the 
ventilating-flues  that  the  products  of  combustion  pass  out  immediately. 
16 


242 


GENERAL    MEDICAL    CHEMISTRY. 


Situation. 

Cubic  metres. 

Cubic  feet. 

Barracks  (day-time  

35 

1,236 

Barracks  (night-time)   

70 

2,472 

Workshops  (mechanical)  

70 

2,472 

35 

1,236 

Hospital  wards  /'.".  -•/.  

85 

3,002 

170 

6  004 

170 

6,004 

Mines,  metalliferous  

150 

5,297 

Mines,  coal  

170 

6,004 

P^ach  cubic  foot  of  illuminating-gas  consumes  in  its  combustion  a  quan- 
tity of  oxygen  equal  to  that  contained  in  7.14  cubic  feet  of  air,  and  pro- 
duces 0.8  cubic  feet  of  carbon  dioxide,  besides  a  large  quantity  of  watery 
vapor,  and  less  amounts  of  sulphuric  acid,  sulphur  dioxide,  and  sometimes 
carbon  monoxide;  and  an  ordinary  gas-burner  consumes  about  three  feet 
per  hour.  It  is  obvious,  therefor,  that  a  much  larger  quantity  of  pure 
air  must  be  furnished  to  maintain  the  atmosphere  of  an  apartment  at  the 
standard  of  0.6  per  1,000  of  carbon  dioxide,  when  the  vitiation  is  produced 
by  the  combustion  of  gas,  than  when  it  is  the  result  of  the  respiration  of  a 
human  being,  and  that  to  such  an  extent  that  a  single  three-foot  burner 
requires  a  supply  of  air  which  would  be  sufficient  for  six  human  beings. 
As  a  basis  for  computation,  it  may  be  considered  that,  for  each  cubic  foot 
of  gas  consumed,  1,800  cubic  feet  of  air  should  be  furnished  by  ventilation. 
The  contamination  of  air  by  gas-lights  becomes  a  question  of  serious 
importance  in  our  dwellings  upon  occasions  of  social  gatherings,  and  in 
theatres  and  other  places  of  public  resort  which  are  used  during  the  hours 
of  darkness.  The  average  size  of  a  parlor  in  a  city  dwelling  is  15  x  25  x  15 
feet;  it  therefor  contains  4,875  cubic  feet,  and  its  atmosphere  would, 
if  it  were  hermetically  closed,  be  brought  to  the  standard  of  maximum 
allowable  contamination  by  the  respiration  of  four  adults  in  an  hour, 
allowing  1,200  cubic  feet  per  head,  per  hour.  If  such  an  apartment  be  illu- 
minated, upon  the  occasion  of  an  evening  party  at  which  fifty  adults  are 
present  for  four  hours,  by  ten  three-feet  gas-burners,  the  amounts  of  air 
which  should  be  supplied  by  ventilation  are  as  follows  in  cubic  feet. 


If  the  products  of  combustion 
of  gas  be  discharged  into  the 
room. 

If  the  products  of  combustion 
of  the  gas  be  carried  off. 

Per  hour. 

Per  hour. 

Per  hour. 

For  four  hours. 

For  fifty  persons  

60,000 
54,000 

240,000 
216,000 

60,000 

240,000 

For  ten  gas-burners  .... 
Totals  

114,000 

456,000 

60,000 

240,000 

In  the  first  instance,  in  which  the  products  of  the  combustion  of  gas 
are  discharged  into  the  apartment,  an  adequate  ventilation  can  only  be 


CAKBON    DIOXIDE.  243 

secured  by  a  complete  change  of  the  air  every  2.6  minutes,  which  can 
only  be  attained  by  the  use  of  mechanical  contrivances,  and  with  the 
production  of  draughts;  in  the  second  instance,  in  which  it  is  presumed 
that  the  gas-burners  are  so  situated,  with  reference  to  a  ventilating-shaft 
or  shafts,  that  the  products  of  combustion  are  immediately  carried  off, 
not  only  is  the  period  in  which  a  complete  change  of  air  is  required  ex- 
tended to  4.8  minutes,  but  the  heat  of  the  burners,  causing  an  uptake 
current  in  the  ventilator,  favors  the  exit  of  the  vitiated  air,  and  the  con- 
sequent entrance  of  external  air  to  take  its  place. 

In  theatres  the  contamination  of  the  air  by  the  burning  of  gas  should 
be  entirely  eliminated  by  placing  the  burners  either  under  the  dome  ven- 
tilator, or  in  boxes  which  open  to  the  air  of  the  house  only  below  the 
level  of  the  burner,  arid  which  are  in  communication  with  a  ventilating- 
shaft.  Even  under  these  conditions  it  is  necessary,  to  ensure  perfect 
ventilation,  to  resort  to  some  mechanical  contrivance  to  remove  the  air 
vitiated  by  respiration  and  to  supply  its  place  by  fresh  air  from  without, 
which  may  be  previously  warmed  or  cooled  according  to  the  season,  and 
which,  in  cities,  should  be  filtered.  In  a  New  York  theatre,  whose  ven- 
tilation has  been  carried  to  such  a  degree  of  perfection  that  the  air  is 
sensibly  as  pure  after  as  before  a  performance,  whose  cubical  contents 
are  about  ninety  thousand  cubic  feet,  and  whose  seating  capacity  is  about 
six  hundred  and  fifty,  there  are  injected  and  aspirated  by  two  blowers, 
one  in  the  cellar  and  one  on  the  roof,  one  million  to  one  million  two  hun- 
dred and  fifty  thousand  cubic  feet  of  air  per  hour,  or  about  one  thousand 
five  hundred  cubic  feet  per  head  per  hour. 

When  artificial  illumination  is  obtained  from  lamps  or  candles,  or  from 
gas  in  small  quantity  and  for  a  short  time,  the  contamination  of  the  air 
is  sufficiently  compensated  by  the  ventilation  through  imperfect  closing 
of  the  windows.  A  room  without  a  window  should  never  be  used  for 
human  habitation. 

One  important  advantage  of  the  electric  light,  if  it  ever  become  prac- 
ticable, will  be  that  it  consumes  no  oxygen  and  produces  no  carbon  di- 
oxide. 

Although,  by  the  combustion  of  fuel,  oxygen  is  consumed  and  carbon 
dioxide  produced,  heating  arrangements  only  become  a  source  of  vitiation 
of  air  under  the  circumstances  detailed  above  (see  p.  235);  indeed,  in  the 
majority  of  cases,  if  properly  arranged,  they  are  means  of  ventilation, 
either  by  aspirating  the  vitiated  air  of  the  apartment,  or  by  the  introduc- 
tion of  air  from  without. 

Action  on  the  economy. — An  animal  introduced  into  an  atmosphere 
of  pure  carbon  dioxide  dies  almost  instantly,  and  without  entrance  of 
the  gas  into  the  lungs,  death  resulting  from  spasm  of  the  glottis,  and 
consequent  apnoea. 

When  diluted  with  air,  the  action  of  carbon  dioxide  varies  according 
to  its  proportion,  and  according  to  the  proportion  of  oxygen  present. 

First. — When  the  proportion  of  oxygen  is  not  diminished,  the  poison- 
ous action  of  carbon  dioxide  is  not  as  manifest,  in  equal  quantities,  as  when 
the  air  is  poorer  in  oxygen.  An  animal  will  die  rapidly  in  an  atmosphere 
composed  of  twenty-one  per  cent.  O,  fifty-nine  per  cent.  N,  and  twenty 
per  cent.  CO2  by  volume;  but  will  live  for  several  hours  in  an  atmosphere 
whose  composition  is  forty  per  cent.  O,  thirty-seven  per  cent.  N,  twenty- 
three  per  cent.  CO2.  If  carbon  dioxide  be  added  to  normal  air,  of  course 
the  relative  quantity  of  oxygen  is  slightly  diminished,  while  its  absolute 
quantity  remains  the  same;  this  is  the  condition  of  affairs  existing  in 


244  GENERAL    MEDICAL    CHEMISTRY. 

nature  when  the  gas  is  discharged  into  the  air;  under  these  circumstances 
an  addition  of  ten  to  fifteen  per  cent,  of  COQ  renders  an  air  rapidly  poi- 
sonous, and  one  of  five  to  eight  per  cent,  will  cause  the  death  of  small 
animals  more  slowly.  Even  a  less  proportion  than  this  may  become  fatal 
to  an  individual  not  habituated. 

In  the  higher  states  of  dilution,  carbon  dioxide  produces  immediate 
loss  of  muscular  power,  and  death  without  a  struggle;  when  more  dilute, 
a  sense  of  irritation  of  the  larynx,  drowsiness,  pain  in  the  head,  giddi- 
ness, gradual  loss  of  muscular  power,  and  death  in  coma. 

Second. — If  the  carbon  dioxide  present  in  air  be  produced  by  respi- 
ration or  combustion,  the  proportion  of  oxygen  is  at  the  same  time  di- 
minished, and  much  smaller  absolute  and  relative  amounts  of  the  poison- 
ous gas  will  produce  the  effects  mentioned  above;  thus,  an  atmosphere 
containing  in  volumes  19.75  per  cent.  O,  74.25  per  cent.  N,  six  per  cent. 
CO2,  is  much  more  rapidly  fatal  than  one  composed  of  twenty-one  per 
cent.  O,  fifty-nine  per  cent.  N,  twenty  per  cent.  CO2.  With  a  corre- 
sponding reduction  of  oxygen,  five  per  cent,  of  carbon  dioxide  renders  an 
air  sufficiently  poisonous  to  destroy  life;  two  per  cent,  produces  severe 
suffering;  one  per  cent,  causes  great  discomfort,  while  0.1  per  cent., 
or  even  less,  is  recognized  by  a  sense  of  closeness. 

The  treatment  in  all  cases  of  poisoning  by  carbon  dioxide  consists  in 
the  inhalation  of  pure  air  (to  which  a  small  excess  of  oxygen  may  be 
added),  aided,  if  necessary,  by  artificial  respiration,  the  cold  douche,  gal- 
vanism, and  friction. 

When  it  chances  that  an  individual  entering  an  atmosphere  contain- 
ing an  excess  of  carbon  dioxide,  or  other  noxious  gas,  is  seen  to  fall  in- 
sensible, it  is  simply  multiplying  the  number  of  victims,  for  others  to  fol- 
low, unprotected,  with  a  view  to  effecting  a  rescue.  Probably  the  most 
readily  obtainable  protection  is  a  towel  saturated  with  lime-water,  and  so 
held  over  the  mouth  and  nostrils  that  the  inspired  air  passes  through  it, 
and  also  through  two  or  three  layers  of  dry  towelling  interposed  between 
the  moistened  part  and  the  skin.  Obviously  this  protection  will  not  be 
efficacious  for  a  long  time,  and  in  situations  where  such  accidents  are 
liable  to  occur,  as  in  mines,  fermenting  cellars,  etc.,  it  cannot  be  too 
strongly  recommended  that  there  be  kept  at  hand  air-pumps,  tubing,  and 
helmets,  such  as  are  used  by  divers,  but  of  lighter  construction,  to  be 
used  by  the  rescuers  upon  such  occasions. 

Detection  of  carbon  dioxide  and  analysis  of  confined  air. — Carbon 
dioxide,  or  air  containing  it,  causes  a  white  precipitate  when  caused  to 
bubble  through  lime  or  baryta  water;  normal  air  contains  enough  of  the 
gas  to  form  a  scum  upon  the  surface  of  these  solutions  when  exposed  to  it. 

It  was  at  one  time  supposed  that  air  in  which  a  candle  continued  to 
burn  was  also  capable  of  maintaining  respiration.  This  is,  however,  by 
no  means  necessarily  true;  a  candle  introduced  into  an  atmosphere  in 
which  the  normal  proportion  of  oxygen  is  contained,  burns  readily  in  the 
presence  of  eight  per  cent,  of  carbon  dioxide;  is  perceptibly  dulled  by 
ten  per  cent.;  is  usually  extinguished  with  thirteen  per  ceut. ;  always 
extinguished  with  sixteen  per  cent.  Its  extinction  is  caused  by  a  less 
proportion  of  carbon  dioxide,  four  per  cent.,  if  the  quantity  of  oxygen 
be  at  the  same  time  diminished.  Moreover,  a  contaminated  atmosphere 
may  not  contain  enough  carbon  dioxide  to  extinguish,  or  perceptibly  dim 
the  flame  of  a  candle,  and  at  the  same  time  contain  enough  of  the  mon- 
oxide to  render  it  fatally  poisonous  if  inhaled. 

The  presence  of  carbon  dioxide  in  a  gaseous  mixture  is  determined  by 


SULPHOCAKBONIC    ACID.  245 

its  absorption  by  a  solution  of  potassium  hydrate;  its  quantity  either  by- 
measuring  the  diminution  in  bulk  of  the  gas,  or  by  noting  the  increase  in 
weight  of  the  alkaline  solution. 

To  determine  the  proportions  of  the  various  gases  present  in  air,  it  is 
made  to  pass  through  a  series  of  tubes  which  have  been  previously 
weighed:  1st,  through  a  U-shaped  tube  containing  fragments  of  pumice- 
stone,  saturated  with  sulphuric  acid;  by  the  increase  in  weight  of  this 
tube  the  amount  of  watery  vapor  is  determined;  2d,  through  a  Liebig's 
bulb-apparatus,  filled  with  a  solution  of  potassium  hydrate.  The  ra- 
pidity of  the  current  should  be  so  regulated  that  about  thirty  bubbles 
a  minute  pass  through  this  apparatus;  3d,  through  a  U-tube  filled  with 
fragments  of  pumice  saturated  with  sulphuric  acid.  Numbers  two  and 
three  are  weighed  together,  the  increase  in  their  weight  is  the  weight  of 
CO2  in  the  volume  of  air  drawn  through  the  apparatus;  every  gram  of 
increase  in  weight  represents  0.50607  litre,  or  31.60356  cubic  inches. 

The  arrangement  of  the  remainder  of  the  absorption  apparatus  differs 
according  to  whether  carbon  monoxide  and  marsh-gas,  or  oxygen,  is  to  be 
determined.  In  the  former  case  the  air  is  next  passed;  4th,  through  a 
tube  of  difficultly  fusible  glass,  filled  with  black  oxide  of  copper,  and 
heated  to  redness,  in  which  the  gases  mentioned  are  converted  into  water 
and  carbon  dioxide;  then  5th,  through  a  U-tube  filled  with  pumice, 
moistened  with  sulphuric  acid,  whose  increase  of  weight  indicates  the 
amount  of  water  so  formed.  Every  gram  of  increase  of  weight  in  this 
tube  represents  0.444  gram,  or  0.621  litre,  or  38.781  cubic  inches  of  marsh- 
gas.  Finally,  the  gas  is  passed,  6th,  through  a  carbon  dioxide  apparatus, 
similar  to  numbers  two  and  three,  from  whose  increase  in  weight  the 
quantity  of  carbon  monoxide  is  calculated,  thus:  first,  2.75  grams  are 
deducted  for  each  gram  of  "marsh-gas  found  by  number  five;  of  the  re- 
mainder, every  gram  represents  0.6364  grams,  or  0.5085  litre,  or  31.755 
cubic  inches  of  carbon  monoxide. 

If  the  percentage  of  oxygen  is  to  be  determined,  the  gas,  after  passing 
from  No.  3,  is  collected  in  a  graduated  tube  and  its  volume  measured;  a 
concentrated  solution  of  potassium  pyrogallate  is  passed  into  the  tube, 
which  is  agitated  without  removing  its  opening  from  the  trough,  allowed 
to  stand,  and  the  volume  again  determined;  the  difference  in  volume  is 
the  quantity  of  oxygen  in  the  original  volume  of  air.  In  both  measure- 
ments the  level  of  liquid  in  the  tube  must  be  the  same  as  that  in  the  trough. 

To  draw  the  air  through  the  absorbing  apparatus,  an  aspirator  is  used, 
and  the  volume  of  air  determined  by  the  volume  of  escaping  water. 


Sulphocarbonic  Acid, 

is  of  interest  as  corresponding  in  constitution  to  the  hypothetical  carbonic 
acid,  sulphur  replacing  oxygen,  but,  unlike  that  acid,  being  capable  of 
existing  free.  It  may  be  obtained  by  treating  an  alkaline  sulphocarbo- 
nate  with  hydrochloric  acid  and  immediately  afterward  with  water,  as  a 
reddish  brown  oily  liquid,  which  is  insoluble  in  water,  and  readily  decom- 
posable into  carbon  disulphide  and  hydrogen  sulphide. 


246  GENERAL    MEDICAL    CHEMISTRY. 


Carbon  Bisulphide. 

Bisulphide  of  carbon,  CS3. — This  substance,  which  bears  the  same  rela- 
tion to  sulphocarbonic  acid  and  the  sulphocarbonates  that  carbon  dioxide 
does  to  the  hypothetical  carbonic  acid  and  to  the  carbonates,  does  not  exist 
in  nature.  It  is  obtained  by  passing  the  vapor  of  sulphur  over  carbon  heated 
to  redness,  and  partially  purified  by  rectification.  It  is  further  purified 
by  agitation  and  twenty-four  hours'  contact  with  one-half  per  cent,  of 
powdered  mercuric  chloride,  decantation,  treatment  with  two  per  cent, 
of  an  odorless  fatty  material,  and  slow  distillation. 

The  pure  product  is  a  colorless  liquid,  which  has  a  peculiar,  but  not 
disagreeable,  ethereal  odor;  the  nauseating  odor  of  the  commercial  bisul- 
phide is  due  to  the  presence  of  another  sulphuretted  body;  boils  at  47°; 
sp.  gr.  1.293;  very  volatile;  its  rapid  evaporation  in  vacuo  produces  a 
temperature  of  —60°;  it  does  not  mix  with  water,  through  which  it  falls 
in  globular  drops.  It  refracts  light  strongly,  and  is  used  to  fill  prisms  used 
in  some  forms  of  spectroscopic  apparatus. 

It  is  highly  inflammable,  and  burns  with  a  bluish  flame,  giving  off  car- 
bon dioxide  and  sulphur  dioxide;  its  vapor  forms  highly  explosive  mix- 
tures with  air,  which  detonate  on  contact  with  a  glass  rod  heated  to  250°. 
Its  vapor  forms  a  mixture  with  nitrogen  dioxide,  which,  when  ignited, 
burns  with  a  brilliant  flame,  rich  in  actinic  rays. 

There  also  exists  a  substance  intermediate  in  composition  between 
carbon  dioxide  and  carbon  disulphide,  known  as  carbon  oxy sulphide,  CSO, 
which  is  an  inflammable,  colorless  gas,  obtained  by  decomposing  potassium 
sulphocyanate  with  dilute  sulphuric  acid. 

Carbon  disulphide  is  now  manufactured  in  large  quantities,  and  is  us-ed 
in  the  arts  to  dissolve  the  ordinary  phosphorus,  remaining  as  an  impurity 
in  the  preparation  of  the  red  variety,  as  a  solvent  of  sulphur  and  india-rub- 
ber, and  for  the  extraction  of  fats  and  oils,  which  it  dissolves  freely. 

Toxicology. — Cases  of  acute  poisoning  by  carbon  disulphide  have 
hitherto  only  been  observed  in  animals;  its  action  is  very  similar  to  that 
of  chloroform. 

Workmen  engaged  in  the  manufacture  of  carbon  disulphide  and  in 
the  vulcanization  of  rubber,  as  well  as  others  exposed  to  the  vapor  of  the 
disulphide,  are  subject  to  a  form  of  chronic  poisoning  which  may  be  di- 
vided into  two  stages.  The  first,  or  stage  of  excitation,  is  marked  by 
headache,  vertigo,  a  disagreeable  taste,  cramps  in  the  legs;  the  patient 
talks,  laughs,  sings,  and  weeps  immoderately,  and  sometimes  becomes 
violently  delirious.  In  the  second  stage  the  patient  becomes  sad  and 
sleepy,  sensibility  diminishes  sometimes  to  the  extent  of  complete  anaes- 
thesia, especially  of  the  lower  extremities,  the  headache  becomes  more  in- 
tense, the  appetite  is  greatly  impaired,  and  there  is  general  weakness  of 
the  limbs,  which  terminates  in  paralysis. 

The  only  remedy  which  has  been  suggested  is  through  ventilation  of 
the  workshops  and  abandonment  of  the  trade  at  the  first  appearance  of 
the  symptoms. 

CH2OH 

Glycollic  Acid,  |  , 

COOH 

is  formed  by  the  oxidation  of  glycol,  by  the  action  of  nitrous  acid  upon 
glvcocol,  and  by  the  action  of  potassium  hydrate  upon  monochloracetic 
acid. 


LACTIC    ACIDS.  247 

It  forms  deliquescent,  acicular  crystals;  very  soluble  in  water;  soluble 
in  alcohol  and  ether;  has  a  strongly  acid  taste  and  reaction;  fuses  at  78°; 
is  decomposed  at  150°;  at  an  intermediate  temperature  it  loses  HaO,  form- 
ing glycollide,  or  glycollic  anhydride,  C2H2O2. 

It  is  a  monobasic  acid.  The  hydrogen  of  the  group  CH2OH  may  be 
replaced  by  an  alcoholic  radical  to  form  other  acids,  such  as  amylglycollic 

CH.O.C.H,, 
acid,    I 

COOH 

Lactic  Acids,  C.H.O.. 

There  are  probably  three,  certainly  two,  acids  having  this  composi- 
tion, which  differ  from  each  other  mainly  in  the  products  of  their  decom- 
position, in  their  physical  properties,  and  in  the  solubility  and  amount  of 
water  of  crystallization  of  their  salts.  They  resemble  each  other  in  being 
colorless,  syrupy  liquids;  insoluble  in  water,  alcohol,  and  ether,  and  very 
acid  in  taste  and  in  reaction. 

Two  of  these  acids  would  seem,  from  their  products  of  decomposition, 
to  be  of  similar  constitution,  while  the  molecular  composition  of  the  third 
is  distinct;  the  two  of  similar  composition  are  sometimes  designated  as 
ethylidene  lactic  acids,  because  of  their  containing  the  group  of  atoms 
CH3,  while  the  third  is  designated  as  ethyleno-lactic  acid,  as  it  contains 
the  group  CH2;  the  composition  is  expressed  by  the  formulae: 

CH3  CHaOH 

CH,OH  CH2 


COOH 


COOH 

Ethylidene  lactic  acid.  Ethyleno-lactic  acid. 

Obviously  it  is  the  ethylene  acid  which  is  the  superior  homologue  of  gly- 
collic acid. 

Ethyleno-lactic  acid. — As  early  as  1807  Berzelius  discovered  in  muscu- 
lar tissue  an  acid  which  he  took  to  be  lactic  acid,  but  which  was  subse- 
quently shown  by  Liebig  to  differ  from  it  in  several  of  its  characters. 
The  latter  chemist  suggested  the  name  of  sarcolactic  acid,  which  it  has 
retained  until  recent  researches  have  shown  that  the  name  must  be 
abandoned,  as  the  acid  in  question  is  a  mhtture  of  two  distinct  acids — 
ethyleno-lactic  and  optically  active  ethylidene  lactic  acid — both  of  which 
differ  from  the  ordinary  lactic  acid  of  fermentation. 

Ethyleno-lactic  acid  may  be  obtained  from  muscular  tissue,  or  better, 
from  Liebig's  extract  of  meat,  by  a  process  described  below  (see  p.  248). 
It  may  also  be  obtained  synthetically  by  a  process  which  indicates  its  con- 
stitution and  the  rationale  of  its  name.  By  the  action  of  potassium 
cyanide  upon  ethylene  chlorhydrate,  the  nitrite  of  the  ethyleno-lactic  acid 
is  formed: 

CH2,C1       ^     CN,      ^     CH2-CN       ^     C1j 
CH2,OH  K  »  CH2-OH  K  > 

Ethylene  Potassium  Cyanhydrin.  Potassium 

chlorhydrate,  cyanide.  chloride. 


248 


GENERAL    MEDICAL    CHEMISTRY. 


The  cyanhydrine  so  obtained,  when  acted  upon  by  caustic  potassa,  is 
decomposed  with  elimination  of  ammonia  and  formation  of  potassium 
ethyleno-lactate : 


ON 

AH. 


H,OH 

Cyanhydrin. 


COOK 


+     £JO     '-+     H|°;     =      CH'          +     NH» 


i: 


Potassium 
hydrate. 


Water. 


Potassium  Ammonia, 

ethyleno-lactate. 


It  is  distinguished  by  the  following  characters:  it  is  optically  inactive, 
as  are  also  solutions  of  its  salts;  its  zinc  salt  contains  two  molecules  of 
water  of  crystallization,  and  is  very  soluble  in  water  and  quite  soluble  in 
alcohol.  When  oxidized  by  chromic  acid  this  acid  yields  malonic  acid,  as 
would  be  expected  from  an  examination  of  the  formulae  of  the  two  acids: 


CHa,OH 


IT. 


CO,OH 
BL 


JO,OH 

Ethyleno-lactic  acid. 


!0,OH 

Malonic  acid. 


Of  the  two  ethylidene  lactic  acids,  that  which  is  optically  active  is  the 
one  accompanying  ethylene  lactic  acid,  and  predominating  over  it  in 
amount  in  dead  muscle;  it  is  to  this  acid  that  the  name  paralactic  acid 
is  most  properly  applied. 

It  may  be  obtained  from  Liebig's  meat  extract;  this  is  dissolved  in 
four  parts  water;  eight  parts  strong  alcohol  are  then  added  during  con- 
stant agitation;  after  standing,  the  clear  liquid  is  decanted  off,  and  the 
insoluble  residue  again  extracted  with  two  parts  of  warm  water,  and  the 
solution  precipitated  with  four  parts  strong  alcohol.  The  united  alcoholic 
fluids  are  evaporated  to  a  thin  syrup  over  the  water-bath,  and  the  residue 
again  precipitated  with  four  volumes  of  strong  alcohol;  the  clear  alco- 
holic fluid  is  evaporated  to  dryness;  the  residue  extracted  with  water;  the 
solution  acidulated  with  dilute  sulphuric  acid  and  shaken  with  successive 
portions  of  ether.  The  ethereal  fluid,  on  evaporation,  leaves  a  mixture  of 
this  acid  and  ethyleno-lactic  acid,  which  is  dissolved  in  water;  the  solu- 
tion is  boiled  with  zinc  oxide,  filtered,  the  filtrate  evaporated  until  crys- 
tals begin  to  form,  when  four  or  five  volumes  of  strong  alcohol  are  added 
and  the  mixture  set  aside;  zinc  paralactate  crystallizes  at  first,  and  is 
thus  separated  from  the  ethyline  lactate,  which  is  much  more  soluble. 
From  the  zinc  salts  the  acids  are  obtained  by  solution  in  water,  decom- 
position by  hydrogen  sulphide,  filtration,  concentration,  extraction  with 
ether,  and  evaporation  of  the  ethereal  solutions. 

Paralactic  acid  differs  from  its  two  isomeres  in  that  its  solutions  are 
dextrogyrous,  and  the  solutions  of  its  salts  are  Isevogyrous.  The  specific 
rotary  power  of  the  acid  is  FVL—  +3.5°;  that  of  the  zinc  salt 


—  7.6°;  and  of  the  calcium 


is  [0]D=  +3.5°; 
i  salt  [«]„=  — 3.£ 


Its  products  of  decomposition  are  ihe  same  as  those  of  ordinary  lactic 
acid. 


LACTIC    ACIDS.  249 

Ordinary  lactic  acid — Lactic  acid  of  fermentation — Optically  inac- 
tive ethylidene  lactic  acid — exists  in  nature,  widely  distributed  in  the 
vegetable  kingdom,  and,  as  its  name  implies,  as  the  product  of  a  fermen- 
tation which  is  designated  as  the  lactic,  in  milk,  sour-krout,  fermented 
beet-juice,  and  rice,  and  in  the  liquid  refuse  of  starch-factories  and  tan- 
neries. 

Lactic  acid  is  obtained  as  a  product  of  the  fermentation  of  certain 
sugars,  milk-sugar  and  grape-sugar,  as  a  result  of  the  processes  of  nutri- 
tion of  a  minute  vegetable,  the  lactic  ferment,  in  which  the  sugar  is  con- 
verted into  its  polymere : 

CeH1206     =     2C3H603 

Grape-sugar.  Lactic  acid. 

The  process  usually  followed  consists  in  allowing  a  solution  composed 
of  cane-sugar,  3  kilos,  tartaric  acid,  15  grams,  water,  13  kilos,  to  stand 
several  days;  60  grams  of  rotten  cheese,  mixed  with  4  kilos  skimmed  milk 
and  1£  kilos  washed  chalk,  are  then  added,  and  the  mass  exposed  to  a 
temperature  of  30° — 35°  for  ten  days,  being  stirred  from  time  to  time; 
10  kilos  of  boiling  water  and  15  grams  of  slacked  lime  are  then  added; 
the  liquid  is  filtered  through  a  cloth,  concentrated,  and  allowed  to  crystal- 
lize; the  calcium  lactate  so  obtained,  purified  by  recrystallization,  is  dis- 
solved in  water  and  decomposed  by  an  equivalent  quantity  of  sulphuric 
acid;  the  clear  watery  fluid  is  neutralized  with  zinc  carbonate.  The  zinc 
lactate  so  formed  is  purified  by  recrystallization,  decomposed  with  hydro- 
gen sulphide,  and  the  liberated  lactic  acid  separated  by  filtration  and  con- 
centration of  the  watery  liquid. 

It  has  also  been  obtained  synthetically  by  oxidation  of  the  propylglycol 
of  Wurtz,  which  is  a  secondary  glycol,  a  synthesis  which  indicates  its 
constitution: 

CH3  CH3 

6HOH     +     Oa     =     CHOH     4-     H,0 

CH2OH  COOH 

ropylglycol.          Oxygen;  Lactic  acid.  Water. 

It  is  a  colorless,  syrupy  liquid;  sp.  gr.  1.215  at  20°;  does  not  solidify 
at  — 24°;  soluble  in  water,  alcohol,  and  ether;  is  not  capable  of  distillation 
without  decomposition;  when  heated  to  130°  it  loses  water  and  is  con- 
verted into  dilactic  acid,  C6H10OB,  and,  when  heated  to  250°,  into  lactide, 
C3H4O?.  It  is  a  good  solvent  of  tricalcic  phosphate. 

Oxidizing  agents  convert  this  acid  into  formic  and  acetic  acids  without 
the  formation  of  any  malonic  acid. 

Physiological. — The  three  lactic  acids  are  widely  disseminated  in  ani- 
mal nature,  either  free  or  in  combination.  Free  lactic  acid  of  fermenta- 
tion occurs  in  the  contents  of  the  small  intestine,  and,  when  vegetable 
food  has  been  taken,  in  the  stomach;  it  is  not,  however,  the  acid  to  which 
the  normal,  unmixed  gastric  juice  owes  its  acidity.  Its  salts  have  been 
found  to  exist  in  the  contents  of  the  stomach  and  those  of  the  intestines, 
chyle,  bile,  parenchymatous  fluid  of  spleen,  liver,  thymus,  thyroid,  pan- 
creas, lungs,  and  brain;  urine.  Pathologically  in  the  blood  in  leucocy- 
thaemia,  pyremia,  puerperal  fever,  and  after  excessive  muscular  effort;  in 


250  GENERAL    MEDICAL    CHEMISTRY. 

the  fluids  of  ovarian  cysts  and  transudations.  In  the  urine  it  is  abundant 
in  phosphorus-poisoning,  in  acute  atrophy  of  the  liver,  and  in  rachitis  and 
osteomalachia. 

Muscular  tissue,  after  death  or  continued  contractions,  contains  the 
mixture  of  acids  known  to  the  older  authors  as  sarcolactic  acid.  Normal, 
quiescent  muscle  is  neutral  in  reaction;  but,  as  soon  as  rigor  mortis  appears, 
or  if  the  muscle  be  tetanized,  its  reaction  becomes  acid  from  the  liberation 
of  sarcolactic  acid.  Whether*  these  acid*  are  formed  de  novo  during  the 
contraction  of  the  muscle,  or  whether  they  are  produced  by  the  decom- 
position of  lactates  existing  in  the  quiescent  muscle,  is  still  undetermined; 
certain  it  is,  however,  that  a  given  quantity  of  muscle  has,  when  separated 
from  the  circulation,  a  fixed  maximum  of  acid-producing  capacity,  which 
is  greater  in  a  muscle  that  has  been  tetanized  during  the  interval  between 
its  removal  and  the  establishment  of  rigor,  than  in  one  which  has  been 
at  rest. 

There  exist  no  grounds  upon  which  to  base  the  supposition  that,  in 
rheumatic  fever,  lactic  acid  is  present  in  the  blood. 

The  remaining  acids  of  this  series  are  not  of  sufficient  practical  inter- 
est to  warrant  further  consideration. 


DIATOMIC  AND  DIBASIC  ACIDS. 

SERIES  CnHan_3O4. 
The  acids  of  this  series  at  present  known  are: 


Oxalic  acid C204H2 

Malonic  acid C3O4H4 

Succinicacid C404H6 

Deoxyglutanic  acid  .  CsO^Ha 


Adipic  acid CeO4Hi0 

Pimelic  acid C704Hi2 

Suberic  acid CB04H14 


Azelaic  acid C904H18 

Sebacic  acid Ci0O4H18 

Roccellic  acid Ci7O4H3a 


They  are  derived  from  the  primary  glycols  by  complete  oxidation; 
they  are  diatomic  and  dibasic,  and  contain  two  groups,  CO,  OH.  They 
form  two  series  of  salts  with  the  univalent  metals,  and  two  series  of 
ethers,  one  of  which  contains  neutral,  and  the  other  acid  ethers.  They 
may  be  obtained  from  the  corresponding  glycols,  or  acids  of  the  preceding 
series,  by  oxidation. 


CO,OH 

Oxalic  Acid,    I  , 

CO,OH 

exists  in  the  oxalates  of  potassium,  sodium,  calcium,  magnesium,  and 
iron;  in  the  juices  of  many  plants,  notably  in  sorrel,  rhubarb,  cinchona, 
oak,  etc.;  as  a  native  ferrous  oxalate — humboldtine;  and  in  small  quan- 
tity in  human  urine. 

It  was  formerly  obtained  from  the  vegetables  in  which  it  exists,  but 
is  now  artificially  prepared,  either  by  oxidizing  sugar  or  starch  by  nitric 
acid,  or  by  the  action  of  an  alkaline  hydrate  in  a  state  of  fusion  upon 
sawdust,  by  which  an  alkaline  oxalate  is  produced.  The  soluble  alkaline 
salt  is  converted  into  the  insoluble  calcium  or  lead  oxalate,  which  is 
washed  and  decomposed  with  an  equivalent  quantity  of  sulphuric  acid  or 


OXALIC    ACID.  251 

with  hydrogen  sulphide;  the  liberated  oxalic  acid  is  purified  by  recrystal- 
lization.  The  product  so  obtained  is  sufficiently  pure  for  industrial  pur- 
poses, but  is  still  contaminated  with  small  quantities  of  potassium  sul- 
phate and  oxalate,  and  calcium  oxalate,  to  separate  which,  when  the  acid 
is  required  pure,  as  for  volumetric  analysis,  the  commercial  acid  is  re- 
peatedly recrystallized  from  water  and  from  alcohol. 

Oxalic  acid  is  also  formed  in  a  number  of  other  reactions:  by  the  oxi- 
dation of  many  organic  substances — alcohol,  glycol,  sugar,  etc.;  by  the 
action  of  potassa  in  fusion  upon  the  alkaline  formiates;  and  by  the  action 
of  potassium  or  sodium  upon  carbon  dioxide. 

It  crystallizes  in  transparent  prisms,  containing  two  molecules  of  water 
of  crystallization,  which  effloresce  on  exposure  to  air,  and  lose  their  water 
slowly  but  completely  at  100°,  or  in  a  dry  vacuum.  It  fuses  at  98°  in  its 
water  of  crystallization;  at  110° — 132°  it  sublimes  in  the  anhydrous  form, 
while  a  portion  is  decomposed;  above  160°  the  decomposition  is  more 
extensive;  water,  the  two  oxides  of  carbon  and  formic  acid,  are  produced, 
while  a  portion  of  the  acid  is  sublimed  unchanged.  It  dissolves  in  15.5 
parts  of  water  at  10°;  in  9.5  parts  at  14°,  and  in  a  smaller  quantity  of 
boiling  water;  the  presence  of  nitric  acid  increases  its  solubility.  It  is 
quite  soluble  in  alcohol.  It  has  a  sharp  taste  and  an  acid  reaction  in 
solution. 

Oxalic  acid  is  quite  readily  oxidized;  in  watery  solution  it  is  converted 
into  carbon  dioxide  and  water,  slowly  by  simple  exposure  to  air,  more 
rapidly,  in  the  presence  of  platinum  black  or  of  the  salts  of  platinum  and 
gold,  under  the  influence  of  sunlight,  or  when  heated  with  nitric  acid, 
manganese  dioxide,  chromic  acid,  bromine,  chlorine,  or  hypochlorous  acid. 
Its  oxidation,  when  it  is  triturated  dry  with  pure  oxide  of  lead,  is  suffi- 
ciently active  to  heat  the  mass  to  redness.  Sulphuric  and  phosphoric  acids 
and  other  dehydrating  agents  decompose  it  into  water  and  the  two  oxides 
of  carbon. 

Oxalic  acid,  or  the  soluble  oxalates,  in  neutral  or  alkaline  solution, 
gives  a  white  precipitate  of  calcium  oxalate  with  any  soluble  calcium  salt. 
The  oxalates  of  silver  and  lead,  and  mercurous  oxalate,  are  also  insoluble 
or  very  sparingly  soluble  in  water. 

Uses. — Oxalic  acid  is  largely  used  in  the  arts,  in  dyeing  and  calico 
printing;  to  clean  copper  utensils;  and  to  remove  stains  of  iron-rust  or  of 
ink.  It  was  at  one  time  used  in  medicine,  but  its  use  has  been  abandoned. 

Toxicology. — Although  certain  oxalates  are  constant  constituents  of 
vegetable  food  and  of  the  human  body,  the  acid  itself,  as  well  as  hydro- 
potassic  oxalate,  is  a  violent  poison  when  taken  internally,  acting  both 
locally  as  a  corrosive  upon  the  tissues  with  which  it  comes  in  contact, 
and  as  a  true  poison,  the  predominance  of  either  action  depending  upon 
the  concentration  of  the  solution.  Dilute  solutions  may  produce  death 
without  pain  or  vomiting,  and  after  symptoms  resembling  those  of  narcotic 
poisoning.  Death  has  followed  a  dose  of  3  j.  of  the  solid  acid,  and  re- 
covery a  dose  of  §  j.  in  solution.  When  death  occurs,  it  may  be  almost 
instantaneously,  usually  within  half  an  hour;  sometimes  after  weeks  or 
months,  from  secondary  causes. 

The  treatment,  which  must  be  as  expeditious  as  possible,  consists  in 
the  administration,  first,  of  lime  or  magnesia,  or  a  salt  of  calcium  or  mag- 
nesium suspended  or  dissolved  in  a  small  quantity  of  water  or  mucilagi- 
nous fluid;  afterward,  if  vomiting  have  not  occurred  spontaneously,  and 
if  the  symptoms  of  corrosion  have  not  been  severe,  an  emetic  may  be 
given.  In  the  treatment  of  this  form  of  poisoning  several  points  of  nega- 


252  GENERAL    MEDICAL    CHEMISTRY. 

tive  caution  are  to  be  observed.  As  in  all  cases  in  which  a  corrosive  has 
been  taken  internally,  the  use  of  the  stomach-pump  is  to  be  avoided. 
The  alkaline  carbonates,  which  may  be  used  as  antidotes  when  the  min- 
eral acids  have  been  ingested,  are  of  no  value  in  cases  of  oxalic  acid  poi- 
soning, as  the  oxalates  which  they  form  are  soluble,  and  almost  as  poison- 
ous as  the  acid  itself.  The  ingestion  of  water,  or  the  administration  of 
warm  water  as  an  emetic,  is  contraindicated  when  the  poison  has  been 
taken  in  the  solid  form  (or  where  doubt^  exists  as  to  what  form  it  was 
taken  in),  as  they  dissolve,  and  thus  favor  the  absorption  of  the  poison. 

Analysis. — In  fatal  cases  of  poisoning  by  oxalic  acid  the  contents  of 
the  stomach  are  sometimes  strongly  acid  in  reaction ;  more  usually,  owing 
to  the  administration  of  antidotes,  neutral,  or  even  alkaline.  In  a  sys- 
tematic analysis  the  poison  is  to  be  sought  for  in  the  residue  of  the  por- 
tion examined  for  prussic  acid  and  phosphorus;  or,  if  the  examination 
for  those  substances  be  omitted,  in  the  residue  or  final  alkaline  fluid  of 
the  process  for  alkaloids  (see  p.  348  et  seq.).  If  oxalic  acid  alone  is 
to  be  sought  for,  the  contents  of  the  stomach,  or  other  substances  if  acidy 
are  extracted  with  water,  the  liquid  filtered,  the  filtrate  evaporated,  the 
residue  extracted  with  alcohol,  the  alcoholic  fluid  evaporated,  the  residue 
redissolved  in  water  (solution  No.  1).  The  portion  undissolved  by  al- 
cohol is  extracted  with  alcohol  acidulated  with  hydrochloric  acid,  the 
solution  evaporated  after  filtration,  the  residue  dissolved  in  water  (so- 
lution No.  2).  Solution  No.  1  contains  any  oxalic  acid  which  may 
have  existed  free  in  the  substances  examined;  No.  2  that  which  existed 
in  the  form  of  soluble  oxalates.  If  lime  or  magnesia  have  been  admin- 
istered as  an  antidote,  the  substances  must  be  boiled  for  an  hour  or  two 
with  potassium  carbonate  (not  the  hydrate),  filtered,  and  the  filtrate 
treated  as  above.  In  the  solutions  so  obtained,  oxalic  acid  is  character- 
ized by  the  following 

Tests. — Silver  nitrate  forms  a  white  precipitate,  readily  soluble  in 
nitric  acid  and  in  ammonia.  The  precipitate  does  not  darken  when  the 
fluid  is  boiled,  but,  when  dried  and  heated  on  platinum  foil,  it  explodes. 
Lime-water  or  solution  of  calcium  chloride  or  sulphate,  form  a  white  pre- 
cipitate, insoluble  in  water,  almost  so  in  acetic  and  oxalic  acid;  readily 
soluble  in  hydrochloric  or  nitric  acid.  The  formation  of  this  precipitate 
in  dilute  solutions  is  favored  by  a  previous  addition  of  ammonium  hydrate. 

Lead  acetate,  in  not  too  dilute  solutions,  produces  a  white  precipitate, 
soluble  in  nitric,  insoluble  in  acetic  acid. 

In  toxical  analyses  it  must  not  be  forgotten  that  small  quantities  of 
oxalates  may  be  introduced  into  the  stomach  as  normal  constituents  of 
the  food. 

In  cases  of  suspected  poisoning  by  oxalic  acid,  the  urine  should  be 
examined  microscopically  for  crystals  of  calcium  oxalate. 

CO,OH 

I 


Malonic  Acid,  CHa      , 
,OH 


C0,< 


is  of  interest  as  a  product  of  oxidation  of  the  corresponding  acid  of 
the  preceding  series,  ethyleno-lactic  acid,  and  as  being  identical  with  an 
acid  obtained  from  tobacco,  and  designated  as  nicotic  acid. 


succmic  ACID.  253 

It  crystallizes  in  prismatic  needles ;  which  fuse  at  140°,  are  decomposed 
at  150°;  and  are  very  soluble  in  water,  alcohol,  and  ether. 


CH2— CO,OH 

Succinic  Acid.  ]  , 

CH2— CO,OH 

was  one  of  the  first  organic  acids  known  to  chemists.  It  exists  in  nature 
in  amber,  coal,  fossil  wood,  and  in  small  quantities  in  animal  and  vege- 
table tissues.  Its  presence  has  been  detected  in  the  normal  urine  after 
the  use  of  fruits  and  of  asparagus,  in  the  parenchymatous  fluids  of  the 
spleen,  thyroid,  and  thymus,  and  in  the  fluids  of  hydrocele  and  of  hydatid 
cysts.  It  is  also  formed  in  small  quantity  during  alcoholic  fermentation. 
It  is  formed  as  a  product  of  oxidation  of  many  fats  and  fatty  acids;  and 
by  synthesis  from  ethylene  cyanide. 

It  may  be  obtained  by  dry  distillation  of  amber,  or,  preferably,  by  the 
fermentation  of  malic  acid.  One  kilo  of  calcic  malate  is  dissolved  in  three 
kilos  of  water,  and  to  the  solution  eighty  grams  of  stale  cheese,  or  250 
c.c.  of  yeast,  are  added.  The  mass  is  exposed  to  a  temperature  of  30° — 
40°,  for  five  to  six  days,  when  succinic  acid  is  formed  according  to  the 
equation: 

3C4H6O5    =    2C4H6O4    +    C2H4O2    +    2CO2    +    H2O 

Malic  acid.  Succinic  acid.  Acetic  acid.      Carbon  dioxide.        Water. 

A  mixture  of  calcium  succinate  and  carbonate  crystallizes  out,  is  washed, 
sulphuric  acid  added  as  long  as  effervescence  occurs,  the  mass  extracted 
with  water,  sulphuric  acid  added  as  long  as  a  precipitate  is  formed,  the 
solution  filtered,  and  the  succinic  acid  allowed  to  crystallize  out. 

It  crystallizes  in  large  prisms  or  hexagonal  plates,  which  are  colorless, 
odorless,  permanent  in  air,  acid  in  taste,  soluble  in  water,  sparingly  so  in 
ether  and  in  cold  alcohol.  It  fuses  at  180°,  and  distils  with  partial  de- 
composition at  235°. 

Succinic  acid  withstands  the  action  of  oxidizing  agents;  reducing 
agents  convert  it  into  the  corresponding  acid  of  the  fatty  series,  butyric 
acid;  with  bromine  it  forms  products  of  substitution;  sulphuric  acid  is 
without  action  upon  it;  phosphoric  anhydride  removes  the  elements  of  a 
molecule  of  water  and  converts  it  into  succinic  anhydride,  C4H4O3. 

The  remaining  acids  of  this  series  may  be  dismissed  with  a  few  words. 

Deoxyglutanic  acid,  C5H8O4 — is  derived  from  glutanic  acid  by  heating 
with  hydriodic  acid.  It  forms  large  crystals,  soluble  in  water.  It  is  iso- 
meric  with  pyrotartaric  acid. 

Adipic  acid,  C6H10O4 — is  formed  by  the  action  of  nitric  acid  upon 
many  fatty  substances;  it  bears  the  same  relation  to  leucic  acid  that  oxalic 
does  to  glycolic  acid.  It  is  soluble  in  water,  alcohol,  and  ether;  fuses  at 
130°. 

JPimelic  acid,  C7H12O4 — is  another  product  of  the  oxidation  by  nitric 
acid  of  fatty  substances,  notably  of  oleic  acid.  It  forms  small  crystals; 
sparingly  solublfe  in  water,  alcohol,  and  ether;  quite  soluble  in  the  same 
liquids  when  hot. 

/Suberic  acid,  C8H14O4 — a  product  of  the  oxidation,  by  nitric  acid,  of 
cork,  oleic,  and  stearic  acids,  and  oils  containing  them.  It  forms  small 


254  GENERAL    MEDICAL    CHEMISTRY. 

crystals,  sparingly  soluble  in  cold  water,  readily  soluble  in  hot  water,  al- 
cohol, and  ether. 

Azelaic  acid,  C9H16O4 — also  known  as  anchoic  acid,  is  formed,  along 
with  the  preceding,  by  oxidation  of  castor-oil. 

Sebacic  acid,  (J10H18O4 — is  a  product  of  the  decomposition  of  oleic  acid 
by  dry  distillation,  and  of  the  action  of  potash  on  castor-oil.  It  crystal- 
lizes in  pearly  needles;  fusible. at  126°;  sparingly  soluble  in  cold  water, 
readily  soluble  in  hot  water,  alc6hol,  an^ether. 

Hoccellic  acid,  C17H32O4 — exists  in  various  lichens,  roccella  tinctoria, 
fuciformis,  etc.,  from  which  litmus  and  orchel  are  prepared.  It  crystal- 
lizes in  colorless  crystals;  fusible  at  132°;  insoluble  in  water;  soluble  in 
alcohol  and  in  ether. 


COMPOUND   ETHERS    OF    THE    ACIDS    OF    THE    SERIES 

CJH2W0S  AND  CnH2n_a04. 

The  members  of  both  of  these  series  contain  two  atoms  of  hydrogen 
replaceable  by  alcoholic  radicals.  In  those  of  the  series  CnH2nO3,  with  the 
exception  of  carbonic  acid,  being  monobasic,  although  diatomic,  it  is  not 
immaterial  which  hydrogen  is  so  replaced;  if  it  be  that  of  the  group 
CH2OH,  the  resulting  compound  is  a  monobasic  acid,  in  which  the  hydro- 
gen of  the  group  COQH  may  be  replaced  by  another  alcoholic  radical  to 
form  a  neutral  ether  of  the  new  acid;  if,  on  the  other  hand,  the  hydrogen 
of  the  group  COOH  be  first  replaced,  a  neutral  compound  ether  is  formed. 
In  the  members  of  the  series  CnH2n_2O4,  which  are  dibasic,  the  substitu- 
tion of  an  alcoholic  radical  for  the  hydrogen  of  either  group  OOOH  pro- 
duces a  monobasic  acid,  in  which  the  hydrogen  of  the  other  COOH  may 
be  replaced  by  another  radical  to  form  a  neutral  ether.  The  following 
formulas  indicate  the  differences  in  the  nature  of  these  compounds: 

CH2OH  CHaOC2H6  CHaOH  CHaOC3H5 

COOH  COOH  COOC2HB        COOC2H5 

Glycolic  acid  Ethylglycolic  acid.  Ethyl  glycolate.       Ethyl  ethylglycolate. 

COOH  COOCaHB  COOCaH6 

COOH  COOH      .  COOC2H5 

Oxalic  acid.  Efchyloxalic  acid.  Ethyl  oxalate. 

None  of  the  many  ethers  of  these  series  are  of  medical  interest. 


ALDEHYDES    AND    ANHYDRIDES    OF    THE    SERIES 

CJI2H08  AND  CnH2n_904. 

In  treating  of  the  monoatomic  compounds,  it  was  stated  that  sub- 
stances existed  corresponding  to  the  fatty  acids,  known  as  aldehydes  and 
anhydrides,  the  former  differing  from  the  acids  in  that  they  contained  the 
group  COH  instead  of  COOH,  the  latter  being  the  oxides  of  the  acid 
radicals.  Similar  compounds  exist  corresponding  to  the  acids  of  these 
two  series. 


AMINES  OF  THE  GLYCOLS.  255 

The  aldehydes  corresponding  to  the  series  CnH2-n03  contain  the  group 
COH  in  place  of  the  group  COOH,  and  as  they  also  contain  the  group 
CH2OH,  they  are  possessed  of  the  double  function  of  primary  alcohol  and 
aldehyde.  Those  of  the  series  CnH2n_2O4  form  two  series;  in  one  of  which 
only  one  of  the  groups  COOH  is  deoxidized  to  COH;  in  the  other,  both. 
Those  of  the  first  series,  still  containing  a  group  COOH,  are  monobasic 
acids  as  well  as  aldehydes: 

CH2OH    CH3OH    COOH     COOH     COH 
COOH     COH      COOH     COH      COH 

Glycolic  acid.        Glycolic  aldehyde.          Oxalic  acid.  Glyoxalic  acid.  Glyoxol. 

While  the  anhydrides  of  the  fatty  series  may  be  considered  as  derived 
from  the  acids  by  the  subtraction  of  the  elements  of  a  molecule  of  water  from 
two  molecules  of  the  acids,  those  of  both  the  series  of  acids  under  consider- 
ation are  derived  from  a  single  molecule  of  the  acid  by  the  subtraction  of 
the  elements  of  a  molecule  of  water: 

CH8  CH3— CO  CH2OH 

COOH  CH3— CO/  COOH 

Acetic  acid.  Acetic  anhydride.  Glycolic  acid. 

CH2V  CHa— COOH  CH  —  CO, 

O°  1  1  >° 

CO  /  CH2— COOH  CH2— CO/ 

Glycolic  anhydride.  Bnccinic  acid.  Snccinic  anhydride. 


None  of  those  substances  are  of  practical  medical  importance. 

AMINES    OF    THE    GLYCOLS. 

ETHTLENIC  COMPOUND  AMMONIAS. 

These  substances  are  derived  from  a  double  molecule  of  ammonia,  or 
of  ammonium  hydrate,  by  the  substitution  of  the  diatomic  radicals  of  the 
glycols  (hydrocarbons  of  the  series  CnH2n)  for  an  equivalent  number  of 
hydrogen  atoms.  They  are  distinguished  from  the  corresponding  com- 
pounds of  the  radicals  of  the  monoatomic  alcohols,  the  monamines,  by  the 
designation  of  diamines. 

When  it  is  considered  that  in  the  formation  of  these  substances  double 
hydrogen  atoms  can  be  replaced  by  diatomic  radicals  to  form  primary, 
secondary,  and  tertiary  amines: 


H 


0,H. 

O.H; 

O.K. 


N. 


. 

Double  ammonia        Ethylene  amine,  Diethylene  amine.  Triethylene  amine. 

molecule.  Primary*  Secondary*  Tertiary. 

that  others  exist  in  which  two  univalent  radicals  replace  a  divalent  rad- 
ical; others,  again,  in  which  atoms  of  hydrogen  have  been  replaced  by 
groups  OH;  and  finally,  that  similar  compounds  of  phosphorus,  arsenic, 


256  GENERAL    MEDICAL    CHEMISTRY. 

and  antimony  exist,  it  is  not  astonishing  that  the  study  of  the  vast  num- 
ber of  substances,  the  possibility  of  whose  existence  is  thus  indicated,  is 
still  in  its  infancy. 

Although  at  present  we  know  of  none  of  these  substances  which  is  of 
medical  interest,  there  is  strong  probability  that  further  investigation  will 
show  some  of  the  natural  alkaloids,  whose  constitution  is  as  yet  unknown, 
to  belong  in  this  class. 


AMIDES  OF  THE  ACIDS   OF  THE   SERIES 

CnH2n03  AND  CnH2n_204. 

This  class  of  substances,  formed  by  the  substitution  of  radicals  of  the 
acids  for  atoms  of  hydrogen  in  ammonia  molecules,  contains  some  sub- 
stances of  the  greatest  medical  interest.  The  radicals  of  the  acids  of  the 
series  CnH2nO3,  except  carbonic  acid,  being  univalent,  form  amides  similar 
in  constitution  to  those  of  the  acids  of  the  series  CnH2MO2  (p.  207). 

In  the  case  of  the  dibasic  acids  no  less  than  three  series  of  amides  are 
known  to  exist;  thus  we  have,  corresponding  to  oxalic  acid: 

CO.  COOH 

I  COOH 


I     >  I 

-N  CO/N,  C0\  | 

H  H~N  C 


)OOH 

n'  TT"^  IT  / 

Oximide.  Oxaraide.  Oxamic  acid.  Oxalic  acid. 

Secondary  monamtde.       Primary  diamide.          Primary  monamide.  Acid. 

In  the  first  of  these,  two  atoms  of  hydrogen  of  a  single  molecule  of 
ammonia  are  replaced  by  the  divalent  radical  of  the«acid;  these  are  dis- 
tinguished as  imides.  Those  of  the  second  series  are  normally  formed 
diamides.  In  the  third  series,  the  univalent  remainder,  left  by  the  re- 
moval of  OH  from  the  acid,  replaces  an  atom  of  hydrogen  in  one  molecule 
of  ammonia,  and  the  resulting  compound,  still  containing  a  group  COOH, 
has  the  functions  of  a  monobasic  acid. 


Amides  of  Carbonic  Acid. 
Carbimide, 


Although  many  chemists  have  regarded  cyanic  acid  (q.  v.)  as  being 
the  imide  of  carbonic  acid,  there  are  many  reasons,  drawn  from  the  methods 
of  formation  and  properties  of  cyanic  acid,  which  lead  us  to  assign  to  it 

CN 
the  constitution    I      ,  rather  than  that  given  above,  and  to  consider  it  as 

OH 
the  isomere  of  the  hitherto  undiscovered  carbimide. 


CARBAMIDE UREA.  25? 


(CO)"  ) 

Carbamide — Urea,       H2  v  Na. 


This  important  substance,  whose  existence  was  suspected  by  Boerhaave 
and  Haller,  was  first  obtained  in  an  impure  form  by  the  younger  Rouelle, 
in  1771,  who  called  it  extractum  saponaceum,  urince;  and  in  a  state  of 
comparative  purity  by  Cruikshank  in  1798.  The  name  urea  was  given  it 
in  1799,  by  Fourcroy  and  Vauquelin.  It  is  of  great  interest,  historically 
as  well  as  medically,  as  being  the  first  in  the  great  catalogue  of  organic 
substances  that  have  been  obtained  by  synthetic  methods,  its  synthesis 
having  been  effected  by  Woehler  in  1828. 

Urea  does  not  occur  in  the  vegetable  world;  it  exists  principally  in 
the  urine  of  man  and  of  the  mammalia;  also  in  smaller  quantity  in  the 
excrements  of  birds,  fishes,  and  some  reptiles;  in  the  human  and  mam- 
malian blood,  chyle,  lymph,  liver,  spleen,  lungs,  brain,  vitreous  and  aque- 
ous humors,  saliva,  perspiration,  bile,  milk,  amniotic  and  allantoic  fluids, 
muscular  tissue,  and  in  serous  fluids  (see  below). 

Urea  is  formed  in  a  number  of  reactions: 

First. — As  a  product  of  decomposition  of  uric  acid  in  various  ways. 

Second. — By  the  oxidation  of  oxamide. 

Third. — By  the  action  of  caustic  potassa,  and  of  other  reagents  upon 
creatin,  sarcosine  being  formed  at  the  same  time: 

C4H9N3Oa     +     H20     =     CONaH4     +     0,H7NOf. 

Creatin.  Water.  Urea.  Sarcosine. 

Fourth. — By  the  limited  oxidation  of  albuminoid  substances  by  potas- 
sium permanganate  (see  below). 

Fifth. — By  the  molecular  transformation  of  its  isomeride,  ammonium 
cyanate: 

CN  (CO)  ) 

ONH4  HJ     ' 

Ammonium  cyanate.  Urea. 

This  is  a  step  in  the  classical  method  of  synthesis  of  Woehler,  and  of 
the  process  now  used  for  the  preparation  of  urea  artificially. 

Sixth. — By  the  action  of  carbon  oxychloride  upon  dry  ammonia. 

Seventh. — By  the  action  of  ammonium  hydrate  on  ethyl  carbonate 
at  180°. 

Eighth. — By  heating  ammonium  carbonate  in  sealed  tubes  to  130°. 

Ninth. — By  the  slow  evaporation  of  an  aqueous  solution  of  hydro- 
cyanic acid. 

Preparation. — Urea  is  obtained  either  from  the  urine,  or  synthetically 
from  ammonium  cyanate. 

1.  From  the  urine. — Fresh  urine  is  evaporated  to  the  consistency  of  a 
syrup  over  the  water-bath;  the  residue  is  cooled  and  mixed  with  an 
equal  volume  of  colorless  nitric  acid  of  sp.  gr.  1.42;  the  crystals  which 
separate  are  washed  with  a  small  quantity  of  cold  water,  and  dissolved  in 
hot  water;  the  solution  is  decolorized,  so  far  as  possible,  without  boiling, 
with  animal  charcoal,  filtered,  and  neutralized  with  potassium  carbonate: 
17 


258  GENERAL    MEDICAL    CHEMISTRY. 

the  liquid  is  then  concentrated  over  the  water-bath,  and  decanted  from 
the  crystals  of  potassium  nitrate  which  separate;  then  evaporated  to  dry- 
ness  over  the  water-bath,  and  the  residue  extracted  with  strong,  hot  alco- 
hol; the  alcoholic  solution,  on  evaporation,  leaves  the  urea  more  or  less 
colored  by  urinary  pigment. 

2.  By  synthesis. — Urea  is  more  readily  obtained  in  a  state  of  purity 
from  potassium  cyanate.  This  is  dissolved  in  cold  water,  and  dry  ammo- 
nium sulphate  is  added  to  the  >  solution*  Potassium  sulphate  crystallizes 
out  and  is  separated  by  decanting  the  liquid,  which  is  then  evaporated 
over  the  water-bath,  fresh  quantities  of  potassium  sulphate  crystallizing 
and  being  separated  during  the  first  part  of  the  evaporation;  the  dry  resi- 
due is  extracted  with  strong,  hot  alcohol;  this,  on  evaporation,  leaves  the 
urea,  which,  by  a  second  crystallization  from  alcohol,  is  obtained  pure. 

Urea  crystallizes  from  its  aqueous  solution  in  long,  flattened  prisms, 
and  by  spontaneous  evaporation  of  its  alcoholic  solution  in  quadratic  prisms 
with  octahedral  ends.  It  is  colorless  and  odorless;  has  a  cooling,  bitterish 
taste,  resembling  that  of  saltpetre;  is  neutral  in  reaction;  soluble  in  one 
part  of  water  at  15°,  the  solution  being  attended  with  diminution  of  tem- 
perature; soluble  in  five  parts  of  cold  alcohol  (sp.  gr.  0.816)  and  in  one 
part  of  boiling  alcohol;  very  sparingly  soluble  in  ether.  W^hen  its  powder 
is  mixed  with  that  of  certain  salts,  such  as  sodium  sulphate,  the  water  of 
crystallization  of  the  salt  separates,  and  the  mass  becomes  soft  or  even 
liquid.  When  pure  it  is  not  deliquescent,  but  is  slightly  hygrometric, 
and  when  it  is  to  be  weighed  it  should  be  dried  at  100°  and  cooled  in  a 
dessicator. 

Decompositions. — When  heated  to  130°,  urea  fuses;  at  a  few  degrees 
above  that  temperature  it  boils,  giving  off  ammonia  and  ammonium  car- 
bonate, and  leaves  a  residue  of  ammelide,  C6H9N9O8.  When  heated  to 
150°— 170°,  it  is  decomposed,  leaving  a  mixture  of  ammelide,  cyanuric 
acid,  and  biuret: 

8CON3H4     =     SCO,     +     C6H9N9O8     -f     7NH3     +     H2O 

Urea.  Carbon  dioxide.  Ammelide.  Ammonia.  Water. 

3CON2H4     =     C303N3H3     +     3NH3 

Urea.  Cyanuric  acid.  Ammonia. 


,  [4     =     C3H6N303     -f     NHS 

Urea.  Biuret.  Ammonia. 

One  of  the  tests  for  urea  is  based  upon  the  formation  of  biuret.  If 
maintained  at  150° — 170°  for  some  time,  a  dry,  grayish  mass  remains,  which 
consists  principally  of  cyanuric  acid.  If,  in  this  reaction,  the  volatile  pro- 
ducts be  condensed,  they  will  be  found  to  contain  urea,  not  that  that  sub- 
stance is  volatile,  but  because  a  portion  of  the  cyanuric  acid  and  ammonia 
have  united  to  regenerate  urea  by  the  reverse  action  to  that  given  above. 

Dilute  aqueous  solutions  of  urea  are  not  decomposed  by  boiling;  but 
if  the  solution  be  concentrated,  or  the  boiling  prolonged  for  a  long  time, 
the  urea  is  partially  decomposed  into  carbon  dioxide  and  ammonia.  The 
same  decomposition  takes  place  more  rapidly  and  completely  when  a  solu- 
tion of  urea  is  heated  under  pressure  to  140°. 

A  pure  aqueous  solution  of  urea  is  not  altered  by  exposure  to  filtered 
air.  If  urine  be  allowed  to  stand,  putrefactive  changes  take  place  under 


CARBAMIDE UREA.  259 

the  influence  of  a  peculiar  organized  ferment,  or  of  a  diastase-like  body 
which  is  a  constituent  of  normal  urine. 

Chlorine  decomposes  urea  with  production  of  carbon  dioxide,  nitrogen, 
and  hydrochloric  acid.  Solutions  of  the  alkaline  hypochlorites  and  hypo- 
bromites  effect  a  similar  decomposition  in  the  presence  of  an  excess  of 
alkali,  according  to  the  equation: 

CON2H4     +     3C10Na     =     CO2     +     2H2O     -f     N2     +     3ClNa 

Urea.  Sodium  Carbon  Water.  Nitrogen.  Sodium 

hypochlorite.  dioxide.  chloride. 

Upon  this  decomposition  are  based  the  quantitative  processes  of  Knop, 
Htifner,  Yvon,  Davy,  Leconte,  etc. 

Nitrous  acid,  or  nitric  acid  charged  with  nitrous  vapors,  decomposes 
urea  according  to  the  equation: 

CON2H4     +     NS03     =     C0a     +     N4     4-     2H,O     (1) 

Urea.  Nitrogen  Carbon  Nitrogen,  Water, 

trioxide.  dioxide. 

or  the  equation: 

2CON2H4     +     N203     =     C03(NH4)2     +     N4     +     CO,     (2) 

Urea.  Nitrogen  Ammonium  Nitrogen.  Carbon, 

trioxide.  carbonate.  dioxide. 

If  the  mixture  be  made  in  the  cold,  of  one  molecule  of  nitrogen  tri- 
oxide to  two  morecules  of  urea,  the  decomposition  is  that  indicated  by 
Equation  2.  If,  on  the  other  hand,  the  trioxide  be  gradually  added  to  the 
previously  warmed  urea  solution  in  the  same  proportion,  half  the  urea  is 
decomposed  while  the  remainder  remains  unaltered,  and,  upon  the  addi- 
tion of  a  further  and  sufficient  quantity  of  the  trioxide,  all  the  urea  is  de- 
composed according  to  Equation  1.  Upon  this  reaction  are  based  the 
processes  of  Grehant,  Boymond,  Draper,  etc. 

When  heated  with  mineral  acids  or  alkalies,  urea  is  decomposed  with 
formation  of  carbon  dioxide  and  ammonia;  if  the  decomposing  agent  be 
an  acid,  carbon  dioxide  is  given  off,  and  an  ammoniacal  salt  remains;  if 
an  alkali,  a  carbonate  of  the  alkaline  metal  remains  and  carbon  dioxide  is 
given  off.  Upon  this  decomposition  are  based  the  processes  of  Heintz 
and  Ragsky,  Bunsen,  etc. 

Compounds. — Urea  forms  definite  compounds,  not  only  with  acids,  but 
also  with  certain  oxides  and  salts.  Of  the  compounds  which  it  forms 
with  acids,  the  most  important  are  those  with  nitric  and  oxalic  acids. 

Urea  nitrate,  CON2H4,HN03,  is  formed  as  a  white  crystalline  mass 
when  a  concentrated  solution  of  urea  is  treated,  in  the  cold,  with  nitric 
acid.  It  is  much  less  soluble  in  water  than  is  urea,  especially  in  the 
presence  of  an  excess  of  nitric  acid.  When  heated  to  140°  it  is  decom- 
posed with  evolution  of  large  quantities  of  carbon  dioxide  and  nitrogen 
monoxide.  It  decomposes  the  carbonates  with  liberation  of  urea.  If  a 
solution  of  urea  nitrate  be  evaporated  over  the  water-bath,  it  is  decom- 
posed, bubbles  of  gas  being  given  off  beyond  a  certain  degree  of  concen- 
tration, and  large  crystals  of  urea,  covered  with  smaller  ones  of  urea 
nitrate,  separate.  Zinc  added  to  a  solution  of  urea  nitrate  causes  its  de- 
composition with  evolution  of  equal  volumes  of  nitrogen  and  carbon  di- 
oxide. 


2 GO  GENERAL    MEDICAL    CHEMISTRY. 

Urea  oxalate,  2CON2H4,H2C204 — separates  as  a  fine,  crystalline  pow* 
der  from  mixed  aqueous  solutions  of  urea  and  oxalic  acid  of  sufficient 
concentration.  It  is  acid  in  taste  and  reaction,  less  soluble  in  cold  water 
than  the  nitrate,  and  less  soluble  in  the  presence  of  an  excess  of  oxalic 
acid  that  in  pure  water.  Its  solution  may  be  evaporated  at  the  temper- 
ature of  the  water-bath  without  suffering  decomposition. 

Of  the  compounds  of  urea  with  oxides,  the  most  interesting  are  those 
with  mercuric  oxide,  three  in  number: 

a.  CON2H4,2HgO  is  formed  by  gradually  adding  mercuric  oxide  to 
a  solution  of  urea  heated  to  near  its  boiling-point;  the  filtered  liquid,  on 
standing  twenty-four  hours,  deposits  crystalline  crusts  of  the  above  com- 
position. 

/?.  CON2H4,3HgO  is  formed  as  a  gelatinous  precipitate  when  mercuric 
chloride  solution  is  added  to  a  solution  of  urea  containing  potassium  hy- 
drate. 

y.  CON2H4,4HgO  is  formed  as  a  white,  amorphous  precipitate  when 
a  dilute  solution  of  mercuric  nitrate  is  gradually  added  to  a  dilute  alka- 
line solution  of  urea,  and  the  excess  of  acid  neutralized  from  time  to 
time.  A  yellow  tinge  in  the  precipitate  indicates  the  formation  of  mer- 
curic subnitrate  after  the  urea  has  been  all  precipitated  (see  Liebig's 
process,  below). 

Of  the  compounds  of  urea  with  salts,  that  with  sodium  chloride  is  the 
only  one  of  importance: 

CON2H4,NaCl,H1J0. — It  is  obtained  in  prismatic  crystals  when  solu- 
tions of  equal  molecules  of  urea  and  sodium  chloride  are  evaporated  to- 
gether. It  is  deliquescent  and  very  soluble  in  water.  ^Its  solution,  when 
mixed  with  solution  of  oxalic  acid,  only  forms  urea  oxalate  after  long 
standing,  or  on  evaporation. 

Physiology. — Urea  is  a  constant  constituent  of  normal  mammalian 
blood  and  urine,  and  is  the  chief  product  of  the  oxidation  of  albuminoid 
substances  which  occur  in  the  body;  the  bulk  of  the  nitrogen  assimilated 
from  the  food  ultimately  making  its  exit  from  the  body  in  the  form  of 
urea  in  the  urine. 

The  determinations  of  the  amount  of  urea  in  the  blood  and  fluids 
other  than  the  urine  are,  owing  to  imperfections  in  the  processes  of 
analysis,  not  as  accurate  as  could  be  desired,  the  error  being  generally  a 
minus  one.  As,  however,  the  results  of  the  same  observer,  using  the 
same  method,  are  comparable  with  each  other,  some  of  the  more  prom- 
inent are  given  in  the  following  table: 


QUANTITY   or  UREA   IN   GRAMS  PER  1,000  PARTS  IN  ANIMAL  FLUIDS 

OTHER   THAN   URINE. 

Normal  blood — dog 0.36  Picard. 

Normal  blood — dog 0.19  Wurtz. 

Normal  blood— dog 0.11—0.58  Treskin. 

Normal  blood — dog 0.24 — 0.53  Munk. 

Normal  blood— dog 0 . 14—0 . 85  Pekelharing. 

Normal  blood — dog 0 .22  Poiseuille  &  Gobley. 

Normal  blood — cow t 0.22  Poiseuille  &  Gobley. 

Normal  blood — cow 0.19  Wurtz. 

Normal  blood — goat 0.17  Meissner  &  Shephard. 


CARBAMIDE UKEA.  261 

Normal  blood — human 0.2  — 0.4     Garngee. 

Normal  blood — human 0.16                Picard. 

Normal  blood — human 0 . 14 — 0 . 18  Gautier. 

Normal  blood — human  placental. .  . .  0.28 — 0.62  Picard. 

Normal  blood — human  foatal 0.27                Picard. 

Blood  of  dog  before  nephrotomy. .  .  .  0.26 — 0.88  Grehant. 

Blood  of  dog,  three  hours  after  ne- 
phrotomy    0 . 45 — 0 . 93  Grehant. 

Blood  of  dog,  twenty-seven  hours  after 

nephrotomy 2 . 06 — 2 . 76  Grehant. 

Human  blood  in  cholera 2.4                  Voit. 

Human  blood  in  cholera 3.6                  Chalvet. 

Human  blood  in  Bright's 15.0                 Bright  &  Babington. 

Lymph — dog 0.16               Wurtz. 

Lymph — cow 0.19                Wurtz. 

Chyle — cow 0.19                Wurtz. 

Milk 0.13               Picard.          A  , 

Saliva 0.35               Picard. 

Bile 0.30               Picard. 

Fluid  of  ascites 0.15                Picard. 

Perspiration 0 .43                Favre. 

Perspiration 0.38                Funke. 

Perspiration 0. 88               Picard. 

The  quantity  of  urea  contained  in  human  urine  under  various  circum- 
stances of  health  and  disease  has  been  the  subject  of  a  great  number  of 
investigations,  and  a  determination  of  the  amount  voided  in  a  given  case 
is  frequently  of  great  importance  to  the  physician,  as  indicating  the 
amount  of  disassimilation  of  nitrogenous  material  occurring  in  the  body 
at  the  time.  Under  normal  conditions  the  quantity  of  urea  voided  in 
twenty-four  hours  is  subject  to  considerable  variations,  as  is  shown  in  the 
subjoined  table: 


AMOUNT  OP  UREA  IN  HUMAN  URINE — NORMAL. 

Grams  in  total 
urine  of  24 
hours. 

Urine  of  sp.  gr.  1009.2 9.88  Millon. 

Urine  of  sp.gr.  1011.6 11.39  Millon. 

Urine  of  sp.  gr.  1019.0 18.58  Boymond. 

Urine  of  sp.  gr.  1026.0 25. 80  Millon. 

Urine  of  sp.  gr.  1027.7 29.70  Millon. 

Urine  of  sp.  gr.  1028.0 27. 08  Boymond. 

Urine  of  sp.  gr.  1029.0 31.77  Millon. 

Urine  of  adult  male  (average) 30.0  Berzelius. 

Urine  of  adult  male  (average) 28 . 052  Lecanu. 

Urine  of  adult  male  (average) 25—32  22 — 35  Neubauer. 

Urine  of  adult  male  (average) 32 — 43  Kerner. 

Urine  of  adult  male  (average) 23  3  35       Vogel. 

Urine  of  adult  male,  animal  food 51 — 92  Franque. 

Urine  of  adult  male,  mixed  food 36 — 38  Franque. 

Urine  of  adult  male,  vegetable  food.    24 — 28  Franque. 

Urine  of  adult  male,  non-nitrogenized  food 16       Franque. 

Urine  of  old  men  84— 86  years 8.11     Lecanu. 

Urine  of  adult  female  (average) 19.116  Lecanu. 


262  GENEKAL    MEDICAL    CHEMISTRY. 

AMOUNT  OF  UREA  IN  HUMAN  URIXE  —  NORMAL  —  Continued. 


hours. 

Urine  of  pregnant  female  ....................  .  .....  30  —  38      Quinquand. 

Urine  of  female,  24  hours  after  delivery  .............  20  —  22       Quiuquand. 

Urine  of  infant,  firsfc  day  ......  .  ....................  0.03  —  0.  04  Quinquand. 

Urine  of  infant,  fifth  day  .....  /'.  .\  ,  ......  ,i  ........  0.  12—0  .  15  Quinquand. 

Urine  of  infant,  eighth  day  ...............  ;:  .........  0.2  —  0.28  Quinquand. 

Urine  of  infant,  fifteenth  day  .......  ................  0.3  —  0.  04  Quinquund. 

Urine  of  child  four  years  old  .......................  4  .  505       Lecanu. 

Urine  of  child  eight  years  old  ......................  13  .  471       Lecanu. 

Urine  of  boy  eighteen  months  old  ...................  8  —  12       Harley. 

Urine  of  girl  eighteen,  months  old  ...................  6  —  9         Harley. 

The  variations  are  produced  by: 

First.  —  Age.  —  In  new-born  children  the  elimination  of  urea  is  insig- 
nificant. By  growing  children  the  amount  voided  is  absolutely  less  thai 
that  discharged  by  adults,  but,  relatively  to  their  weight,  considerably 
greater;  thus,  Harley  gives  the  following  amounts  of  urea  in  grams  fo; 
each  pound  of  body-weight  in  twenty-four  hours:  boy,  eighteen  months 
0.4;  girl,  eighteen  months,  0.35;  man,  twenty-seven  years,  0.25;  woman 
twenty-seven  years,  0.20.  During  adult  life  the  mean  elimination  of  urej 
remains  stationary,  unless  modified  by  other  causes  than  age.  In  old  ag( 
the  amount  sinks  to  below  the  absolute  quantity  discharged  by  growing 
children. 

Second.  —  Sex.  —  At  all  periods  of  life  females  eliminate  less  urea  thar 
males.  The  proportion  given  by  Beigel  differs  slightly  from  that  of  Har 
ley,  viz.:  one  kilo  of  male,  0.35  grams  urea  in  twenty-four  hours;  one  kil( 
of  female,  0.25  grams.  During  pregnancy  females  discharge  more  ure? 
than  males;  very  shortly  after  delivery  the  amount  sinks  to  the  normal 
below  which  it  passes  during  lactation. 

Third.  —  Food.  —  The  quantity  of  urea  eliminated  is  in  direct  proper 
tion  to  the  amount  of  nitrogen  contained  in  the  food.  The  ingestion  o 
large  quantities  of  watery  drinks  increases  the  amount,  and  a  contrary 
effect  is  produced  by  tea,  coffee,  and  alcohol.  With  insufficient  food  th( 
excretion  of  urea  is  diminished,  although  not  arrested,  even  in  extreme 
starvation. 

Fourth.  —  Exercise.  —  The  question  whether  the  elimination  of  urea  ii 
increased  during  violent  muscular  exercise  is  one  which  has  been  the  sub 
ject  of  many  observations  and  of  much  discussion.  An  examination  ol 
the  various  results  shows  that,  while  the  excretion  of  urea  is  slightly 
greater  during  violent  exercise  than  during  periods  of  rest,  that  increase 
is  so  insignificant  in  comparison  to  the  work  done,  and,  in  some  instances, 
to  the  loss  of  body-weight,  as  to  render  the  assumption  that  musculai 
force  is  the  result  of  the  oxidation  of  the  nitrogenized  constituents  oi 
muscle  improbable.  (See  Gamgee:  Physiological  Chemistry,  i.,  pp.  385  — 
401,  for  a  full  review  of  the  subject.) 

The  percentage  of  urea  in  the  urine  of  the  same  individual  is  not  the 
same  at  different  times  of  the  day.  The  minimum  hourly  elimination  is 
in  the  morning  hours;  an  increase  begins  immediately  after  the  principal 
meal,  and  reaches  its  height  in  about  six  hours,  when  a  diminution  sets  in 
and  progresses  to  the  time  of  the  next  meal.  Gorup-Besanez  gives  a 
curve  representing  the  hourly  variations  in  the  elimination  of  urea,  which, 
reduced  to  figures,  gives  the  following: 


CARBAMIDE — LUBEA. 


263 


Hour. 

Urea 
in 
grama. 

Hour. 

Urea 
in 
grams. 

Hour. 

Urea 
in 
grams. 

8-9  A  M 

1.5 

4-  5  P  M 

2.6 

121AM  

1   9 

910AM 

1  5 

5-  6   P.  M    

3  1 

1-2  A.M  

1.9 

10    11   A  M 

1  4 

6-  7  P  M 

2  8 

2-3  A  M.. 

1.9 

HAM    12  M 

1  3 

7-  8  P.M 

2  5 

3-4  AM. 

1  8 

12  M     IP  M 

1  8 

8-  9  P  M     

2  3 

4-5  A  M  

1  6 

1-2   P  M           .... 

1  9 

9-10  P.M  

2  0 

5-0  A.M  

1  6 

2  3  P  M 

2  1 

10-11    P  M 

2  0 

6-7  A.M 

1  6 

3  4  p  M 

2.3 

11-12   P  M 

2  3 

7-8  A.M 

1  5 

The  total  of  which,  however,  represents  a  quantity  above  the  normal. 

The  absolute  amount  of  urea  eliminated  in  twenty-four  hours  is  in- 
creased by  the  exhibition  of  diuretics,  alkalies,  colchicum,  turpentine, 
rhubarb,  alkaline  silicates,  and  compounds  of  antimony,  arsenic,  and  phos- 
phorus. It  is  diminished  by  digitalis,  cafein,  potassium  iodide,  and  lead 
acetate;  not  sensibly  affected  by  quinine. 

Pathologically  the  quantity  of  urea  voided  may  be  either  increased  or 
diminished:  an  increase  above  the  normal  indicating  an  increased  oxida- 
tion of  nitrogenous  material  or  the  retention  of  the  urea  formed  within 
the  body;  and  a  diminution  a  deficient  oxidation  of  the  same  class  of  sub- 
stances, or,  as  is  frequently  the  case,  a  diminution  in  the  supply  of  nitro- 
gen to  the  body  from  loss  of  appetite  or  power  of  assimilation. 

In  acute  febrile  diseases  both  the  relative  and  absolute  amounts  of 
urea  eliminated  augments,  with  some  oscillations,  until  the  fever  is  at  its 
height;  there  is,  however,  no  constant  relation  between  the  amount  of 
urea  eliminated  and  the  body  temperature.  During  the  period  of  defer- 
vescence, the  amount  of  urea  eliminated  in  twenty-four  hours  is  diminished 
below  the  normal;  during  convalescence  it  again  slowly  increases.  If  the 
malady  terminate  in  death  the  diminution  of  urea  is  continuous  to  the 
end.  In  intermittent  fever  the  amount  of  urea  discharged  is  increased  on 
the  day  of  the  fever  and  diminished  during  the  interval.  In  cholera,  dur- 
ing the  algid  stage,  the  elimination  of  urea  by  the  kidneys  is  almost  com- 
pletely arrested,  while  the  quantity  in  the  blood  is  greatly  increased. 
When  the  secretion  of  urine  is  again  established,  the  excretion  of  urea  is 
greatly  increased  (sixty  to  eighty  grams  a  day),  and  the  abundant  perspira- 
tion is  also  rich  in  urea.  In  cardiac  diseases,  attended  with  respiratory  diffi- 
culty, but  without  albuminuria,  the  elimination  of  urea  is  diminished  and 
that  of  uric  acid  increased.  In  nephritis,  attended  with  albuminuria,  the 
elimination  of  urea  at  first  remains  normal;  later  it  diminishes,  and  the 
urea,  accumulating  in  the  blood,  gives  rise  to  urcemic  poisoning.  The 
quantity  of  urea  in  the  urine  is  also  diminished  in  all  diseases  attended 
with  dropsical  effusions;  it  is  increased  when  the  dropsical  fluid  is  reab- 
sorbed.  In  true  diabetes  the  amount  of  urea  in  the  urine  of  twenty-four 
hours  is  greater  than  normal.  In  chronic  diseases  the  elimination  of  urea 
is  below  the  normal,  owing  to  imperfect  oxidation. 

Tests  for  urea. — To  detect  the  presence  of  urea  in  a  fluid,  it  is  mixed 
with  three  to  four  volumes  of  alcohol,  and  filtered  after  having  stood 
several  hours  in  the  cold;  the  filtrate  is  evaporated  on  the  water-bath,  and 
the  residue  extracted  with  strong  alcohol;  the  filtered  alcoholic  fluid  is 
evaporated,  and  the  residue  tested  as  follows: 

First. — A  small  portion  is  heated  in  a  dry  test-tube  to  about  1GO°, 


264  GENERAL    MEDICAL    CHEMISTRY. 

until  the  odor  of  ammonia  is  no  longer  observed;  the  residue  is  treated 
with  a  few  drops  of  caustic  potassa  solution  and  three  or  four  drops  of 
cupric  sulphate  solution.  If  urea  be  present,  the  biuret  resulting  from 
its  decomposition  by  heat  (p.  258)  causes  the  solution  of  the  cupric  oxide 
with  a  reddish  violet  color. 

Second. — A  portion  of  the  residue  is  dissolved  in  a  drop  or  two  of 
water  and  an  equal  quantity  of  colorless  concentrated  nitric  acid  added ; 
if  urea  be  present  in  sufficient  quantity^there  appear  white,  shining,  hex- 
agonal or  rhombic  crystalline  plates  or  six-sided  prisms  of  urea  nitrate. 

Third. — A  portion  dissolved  in  water,  as  in  second,  is  treated  with  a 
solution  of  oxalic  acid;  rhombic  plates  of  urea  oxalate  crystallize. 

Determination  of  quantity  of  urea  in  urine. — It  must  not  be  forgotten 
that,  in  all  quantitative  determinations  of  constituents  of  the  urine,  the 
question  to  be  solved  is  not  how  much  of  that  constituent  is  contained  in 
a  given  quantity  of  urine,  but  how  much  of  that  substance  the  patient  is 
discharging  in  a  given  time,  usually  twenty-four  hours.  Quantitative 
determinations  are,  therefor,  in  most  cases,  barren  of  useful  results,  un- 
less the  quantity  of  urine  passed  by  the  patient  in  twenty-four  hours  is 
known;  and,  in  view  of  diurnal  variations  in  elimination,  unless  the 
urine  examined  be  a  sample  taken  from  the  mixed  urine  of  twenty-four 
hours. 

There  is  no  substance  in  the  body  for  whose  quantitative  determina- 
tion so  many  processes  have  been  suggested;  yet,  although  some  of  these 
are  sufficiently  accurate  for  clinical  purposes,  there  has  been  none  hitherto 
devised,  which,  as  applied  to  the  urine,  is  free  from  sources  of  error. 

The  processes  giving  the  most  accurate  results  are  those  of  Bunsen 
and  Draper,  in  both  of  which  the  urea  is  decomposed  into  carbon  dioxide 
and  ammonia,  the  former  of  which  is  weighed  as  barium  carbonate.  Un- 
fortunately, both  processes  require  an  expenditure  of  time  and  a  degree 
of  skill  in  manipulation,  which  render  their  application  possible  only  in 
a  well-appointed  laboratory. 

A  process  which  is  described  in  all  the  text-books  upon  urinary  analy- 
sis, and  which  is  much  used  by  physicians,  is  that  of  Liebig.  As  this 
method  is  one,  however,  which  contains  more  sources  of  error  than  any 
other,  and  as  it  can  only  be  made  to  yield  approximately  correct  results 
by  a  very  careful  elimination,  as  far  as  possible,  of  those  defects,  it  is  not 
one  which  is  adapted  to  the  use  of  the  physician. 

Probably  the  most  satisfactory  process  in  the  hands  of  the  practi- 
tioner is  that  of  Hiifner,  based  upon  the  reaction,  to  which  attention  was 
first  called  by  Knop,  of  the  alkaline  hypobromites  upon  urea  (p.  259); 
using,  however,  Dietrich's  apparatus,  or  the  more  simple  modification 
suggested  by  Rumpf,  in  place  of  that  of  Hiifner.  The  apparatus  consists 
of  a  burette  of  30 — 50  c.c.  capacity,  immersed  in  a  reversed  position  in  a 
glass  cylinder,  filled  with  water,  and  of  such  size  that  the  burette  can  be 
completely  immersed.  The  nozzle  of  the  burette  is  connected  with  a  piece 
of  stout  glass  tubing  about  six  inches  long,  bent  a-t  a  right  angle  at  about 
two  inches  from  its  upper  end,  and  held  by  a  support  in  such  a  way  that 
the  burette,  which  is  to  act  as  a  gasometer,  may  be  elevated  or  depressed 
at  pleasure;  the  other  end  of  the  glass  tubing  is  fitted  to  a  piece  of  rub- 
ber tubing  about  three  feet  long.  The  other  end  of  the  rubber  tube  is 
connected  with  a  short  piece  of  glass  tubing,  which  passes  through  an 
opening  in  a  rubber  cork,  which  has  another  hole  giving  passage  to  a 
short  piece  of  glass  tube  fitted  with  a  rubber  tube  closed  with  a  pinch- 
cock;  the  rubber  cork  is  inserted  into  the  mouth  of  a  wide-mouthed  flask 


CARBAMIDE UREA.  265 

of  about  75  c.c.  capacity;  a  short  test-tube,  of  about  15  c.c.  capacity, 
and  of  such  size  that  it  may  be  made  to  stand  inside  the  bottle  without 
spilling  its  contents;  all  joints  must  be  air-tight. 

The  reagent  required  is  made  as  follows:  27  c.c.  of  a  solution  of 
caustic  soda,  made  by  dissolving  one  hundred  grams  NaHO  in  250  c.c. 
H2O,  are  brought  into  a  glass-stoppered  bottle,  2.5  c.c.  bromine  are 
added,  the  mixture  shaken,  and  diluted  with  water  to  150  c.c.  The  caus- 
tic soda  solution  may  be  kept  in  a  glass-stoppered  bottle,  whose  stopper 
is  well  paraffined,  but  the  mixture  must  be  made  up  as  required. 

To  conduct  a  determination,  about  20  c.c.  of  the  hypobromite  solution 
are  placed  in  the  decomposing-bottle;  5  c.c.  of  the  urine  to  be  examined 
are  placed  in  the  test-tube,  which  is  then  introduced  into  the  bottle,  care 
being  taken  that  no  urine  escapes,  the  cork  is  then  inserted,  the  pinch- 
cock  opened  and  the  burette  adjusted  in  the  cylinder  so  that  the  level  of 
the  water  cuts  the  highest  point  in  the  graduation.  The  pinch-cock  is 
now  closed  and  the  decomposing  bottle  inclined  and  shaken,  so  that  the 
urine  and  hypobromite  solution  mix;  the  decomposition  begins  at  once, 
and  the  evolved  nitrogen  passes  into  the  burette,  which  is  raised  from 
time  to  time,  so  as  to  keep  the  external  and  internal  levels  of  water  about 
equal;  the  carbon  dioxide  formed  is  retained  by  the  soda  solution.  In 
about  an  hour  (the  decomposition  is  usually  complete  in  fifteen  minutes, 
but  it  is  well  to  wait  an  hour)  the  height  is  so  adjusted  that  the  inner 
and  outer  levels  of  water  are  exactly  even  and  the  graduation  is  read, 
while  the  standing  of  the  barometer  and  thermometer  are  noted  at  the 
same  time. 

In  calculating  the  percentage  of  urea  from  the  volume  of  nitrogen 
obtained,  it  is  essential  that  a  correction  should  be  made  for  differences 
of  temperature  and  pressure,  without  which  the  result  from  an  ordinary 
sample  of  urine  may  be  vitiated  by  an  error  of  ten  per  cent.  If,  however, 
the  temperature  and  barometric  pressure  have  been  noted,  the  correction 
is  readily  made  by  the  use  of  the  table  on  pages  266  and  267,  computed 
by  Dietrich. 

In  the  square  of  the  table  in  which  the  horizontal  line  of  the  observed 
temperature  crosses  the  vertical  one  of  the  observed  barometric  pressure 
will  be  found  the  correct  weight,  in  milligrams,  of  a  cubic  centimetre  of 
nitrogen;  this,  multiplied  by  the  observed  volume  of  nitrogen,  gives  the 
weight  of  nitrogen  furnished  by  the  urea.  But  as  60  parts  of  urea  yield 
28  of  nitrogen,  the  weight  of  nitrogen  multiplied  by  2. 14  gives  the  weight 
of  urea  in  milligrams  contained  in  the  5  c.c.  (or  other  quantity)  of  urine 
decomposed.  This  quantity,  multiplied  by  twice  the  amount  of  urine 
passed  in  24  hours,  and  divided  by  1,000,  gives  the  amount  of  urea 
eliminated  in  24  hours  in  grams. 

Example. — 5  c.c.  of  urine  decomposed;  barometer  =  742 ;  thermom- 
eter=20;  nitrogen  collected— 14.5. 

From  the  table,  the  weight  of  1  c.c.  N  at  the  above  temperature  and 
pressure  is  1.116.  1.116  X  14.5  =  16.18  milligr.  nitrogen  collected;  16.18  X 
2.14=34.625  milligr.  urea  in  6  c.c.  urine.  The  patient  passed  in  24  hours  650 

1300x34.63     AKM  ,  .     0.  , 

c.c.  urine,  =45.02  grams  urea  passed  in  24  hours. 

1,000 

In  using  this  process  it  is  well  to  have  the  urea  solution  as  near  the 
strength  of  one  per  cent,  as  possible;  therefor,  if  the  urine  be  concentrated, 
as  in  the  above  example,  it  should  be  diluted.  Even  when  carefully  con- 
ducted, the  process  is  not  strictly  accurate;  creatinin  and  uric  acid  are 
also  decomposed  with  liberation  of  nitrogen,  thus  causing  a  slight  plus 


266 


GENERAL   MEDICAL    CHEMISTRY. 


TABLE  OP  THE  WEIGHT  OF  ONE 


720 

722 

724 

726 

728 

730 

732 

734 

736 

738 

740 

742 

744 

r!0° 
11° 

.  1338 

.1288 

1.1370 
1.1320 

1.1402 
.1352 

1.1434 

1.1384 

1.1466 
1>1415 

1.1498 
1.1447 

1.1529 
1  1479 

1.1561 
1.1511 

1.1593 
1.1542 

1.1625 

1.1574 

1.1657 
1.1606 

1.1689 
1.1638 

1.1721 

.1670 

1 

12° 

13° 

.1237:1.1269 
.1187;  1.1219 

.1301J  1.1333 
.1251  1.1282 

1.1364  fl  .13961  13428  ,  1  .1459  1  .1491 
1.1314  1.1345  1.1377  1.1409  1.1440 

1.1523 
1.1472 

1  1554  !  1.1586 
1.1503  11.1535 

.1618 
.1566 

$f 

14° 

.1136  1.1168     .1200     .1231 

1.1263 

1.1294 

1.1326  1.1857  1.1389 

1.1420 

1.1452 

1  1483 

.1515 

I 

15" 

.1085  1.1117 

.1149     .1180 

1.1211 

1.1243 

1.1274  1  1305  1.  1&>7 

1.1868 

1.1399 

1.1431 

.1462 

0 

16° 

j    .1034  1.1066 

.1097!    .1128 

1.1160  1.1191 

1.  1222  jl.  1253  i  1.1285 

1.1316 

1.1347 

1.1378 

.1409 

£  j 

17° 

'    .0983     .1014 

.1045     .1076 

1.1107  1.1138 

1.117011  1201  1.1232 

1.1263 

1.1294 

1.1325 

.1356 

«  1  18° 

.0930     .0961 

.0992:    .1023 

.1054  1.1085 

1.1117  1.1148 

1.1179 

1.1209 

.1241 

1.1272 

.1303 

c 

19° 

.0877     .0<H)8 

.0939  1.0970 

.1001   1.1032 

1.1U63 

1.1094  1.1125 

1.1156 

.1187 

1.1218 

.1248 

f 

20" 

.0885,    .0865     .0886  1.0917 

.0948  1.0979 

1.1009 

1.1040  1.1071 

1.1102 

.1133 

1.1164 

.1194 

21" 

.07711    .0802     .0832  1.0863  1.0894  1.0924  1  .  0955  !  1  .  0986  1.1017  1.10471     1078  1  1109 

.1139 

5" 

22° 

I    .0717 

.0  T47     .0778  1  .0808     .0839  1  .0870  1  .0900  j  1  0931  1  .0%!     .0992  1     1023  1  1053 

.1084 

1 

23° 

!    .0662 

.0692     .0723  1.0753:    .0784  1  .08141  1  .0845  !  1  0875 

1.0916      0936 

0967  !1  C997 

.1028 

H 

24° 

:    .  06'  ifi  11.0636  1.0667  1.0697     .0728  1.0758  1.0789  j  1  08191  1.0849     .0880 

.0910 

1.0940 

.0971 

25° 

1.0550 

1  0580 

1.0610 

1.0641 

.0671 

1  .0701 

1.0732 

1.0762 

1.0792 

.0823 

.0853 

1.0883 

.0913 

720 

722 

724 

726 

728 

730 

732 

734 

736 

738 

740 

742 

744 

Barometric  pressure  in  millimetres. 

error;  on  the  other  hand,  a  minus  error  is  caused  by  the  fact,  that  in  the 
decomposition  of  urea  by  the  hypobromite,  the  theoretical  result  is  never 
obtained  within  about  eight  per  cent,  in  urine.  These  errors  may  be 
rectified  to  a  great  extent  by  multiplying  the  result  by  1.044. 

A  process  which  does  not  yield  as  accurate  results  as  the  preceding, 
but  which  is  much  more  easy  of  application,  is  that  of  Fowler,  based  upon 
the  loss  of  specific  gravity  of  the  urine  after  the  decomposition  of  its 
urea  by  hypochlorite.  To  apply  this  method  the  specific  gravity  of  the 
urine  is  carefully  determined,  as  well  as  that  of  the  liq.  sodae  chlorinatae 
(Squibb's).  One  volume  of  the  urine  is  then  mixed  with  exactly  seven 
volumes  of  the  liq.  sod.  chlor.,  and,  after  the  first  violence  of  the  reaction 
has  subsided,  the  mixture  is  shaken  from  time  to  time  during  an  hour, 
when  the  decomposition  is  complete;  the  specific  gravity  of  the  mixture 
is  then  determined.  As  the  reaction  begins  instantaneously  when  the 
urine  and  reagent  are  mixed,  the  specific  gravity  of  the  mixture  must  be 
calculated  by  adding  together  once  the  specific  gravity  of  the  urine  and 
seven  times  the  specific  gravity  of  the  liq.  sod.  chlor.,  and  dividing  the 
sum  by  eight.  From  the  quotient  so  obtained  the  specific  gravity  of  the 
mixture  after  decomposition  is  subtracted;  every  degree  of  loss  in  spe- 
cific gravity  indicates  0.7791  gram  of  urea  in  100  c.c.  of  urine.  The 
specific  gravity  determinations  must  all  be  made  at  the  same  tempera- 
ture; and  that  of  the  mixture  only  when  the  evolution  of  gas  has  ceased 
entirely. 

Finally,  when  it  is  only  desired  to  determine  whether  the  urea  is 
greatly  in  excess  or  much  below  the  normal,  advantage  may  be  taken  of 
the  formation  of  crystals  of  urea  nitrate.  Two  samples  of  the  urine  are 
taken,  one  of  5  c.c.  and  one  of  10  c.c.;  the  latter  is  evaporated,  at  a  low 
temperature,  to  the  bulk  of  the  former  and  cooled;  to  both  one-third 
volume  of  colorless  nitric  acid  is  added.  If  crystals  do  not  form  within  a 
few  moments  in  the  concentrated  sample,  the  quantity  of  urea  is  below 
the  normal;  if  they  do  in  the  unconcentrated  sample,  it  is  in  excess.  In 
using  this  very  rough  method,  regard  must  be  had  to  the  quantity  of 


COMPOUND    UKEAS. 


267 


CUBIC  CENTIMETRE  OP  NITROGEN. 


746 

748 

750 

752 

754 

756 

758 

760 

762 

764 

766 

768 

770 

1  1753 

1.1785 

1.1S17 

1.1848 

.1880 

1  .1912 

.1944 

1.1976 

1.2008 

1.2040 

1.2072 

1  2104 

1.2136 

10"  i 

1.1701 

1.1733 

.1165 

1.1717 

.1829 

1.  18*50 

.1892 

1.1924 

1.1958 

1.1988 

1  2019 

1.2051  11.2063 

II" 

j 

.1649 

1.1681 

.1713 

1.1744 

.1776 

1.1808 

.1839 

.1871 

1.1903 

.1934 

.1966 

1  1998  1.2029 

12° 

0 

.1598 

1.1630 

.1651 

1.1693 

.1724 

1.1756 

.1787 

.1819 

1.1851 

.1882 

.1914 

1.1945 

1.1977 

13° 

8 

.154(5 

1.1577 

.16U9 

1640 

.1672 

1.1703 

.1735 

.1166 

1.1798 

.1829 

.1861 

1.1892 

1.1923 

14° 

0 

.1493 

1  1525 

.155(5 

.1587 

.1619 

1.1650 

.1681 

.1713 

1.1744 

.1775 

.1807 

1.1838 

1.1869 

15° 

3 

.1441 

1  147v> 

.1503 

.1534 

.1566 

1.1597 

.1628|    .1659 

1.1691 

.1722!    .1753 

1.1784 

1.1816 

16° 

3" 

1397 

1.1419 

.1450 

.1481 

.1512 

1.1543 

.1574 

.1605 

1.1636 

.1667!    .1699 

1.1730 

1.1761 

17° 

n> 

.1334 

1.136.-> 

.139(5 

.1427 

.1458 

1.1489 

.1520 

.1551 

1.1582 

.1613!    .1644 

1.167511.1706 

18° 

5" 

.1279 

1.1310 

.1341 

.1372 

1.1403 

1.1434 

1.1465 

.1496 

1.1527 

.1558 

.1589 

1  1620 

1.1650 

19° 

o 

.1225 

1.12  6 

.1287 

.1318 

1.1348 

1.1379 

1.1410 

.1441 

1.1472 

.1502 

.1533 

1.1564 

1.1595 

20" 

3 

1.117U 

1201 

.  1231 

1.1262 

1.1293 

1.1324 

1.1854 

.1385 

1.1416 

.1446 

.1477 

1.1508  1.1539 

21° 

£T. 

1.1115 

.1145 

.1176 

1.1206 

1.1237 

1.1968 

1.1298 

.1329 

1.1359 

1.1390 

1.1421 

1.1451 

1.1482 

22° 

^ 

1.1058 

.1089 

.1119 

1.1150 

1.1180 

1.1211 

1.1241 

.1272 

1.1302 

1  .1333 

1.1363 

1.1394 

1  .1424 

23° 

^ 

1.1001 

.1032 

.1062 

1.1092 

1.1123 

1.1153 

1.1184 

1.1214 

1.1244 

1.1275 

1.1305 

1.1386 

1.1366 

24° 

? 

1.0944 

.0974 

1.1004 

1.1035 

1.1065 

1.1095 

1.1126 

1.1156 

1.1186 

1.1216 

1.1247 

1.1277 

1.1307 

25° 

• 

746 

748 

750 

752 

754 

756 

758 

760 

762 

764 

766 

768 

770 

Barometric  pressure  in  millimetres. 

urine  passed  in  twenty-four  hours;  the  above  applies  to  the  normal 
amount  of  1,200  c.c. ;  if  the  quantity  be  greater  or  less,  the  urine  must 
be  concentrated  or  diluted  in  proportion. 

Obviously  this  process  cannot  be  used  when  the  urine  is  albuminous. 


Sulphurea, 


is  a  compound  bearing  the  same  relation  to  urea  that  carbon  disul- 
phide  bears  to  carbon  dioxide,  and  may  be  obtained  from  ammonium  sul- 
phocyanate  as  urea  is  obtained  from  ammonium  cyanate.  It  forms  large 
prismatic  crystals  or  long  needles,  very  soluble  in  water  and  alcohol,  dif- 
ficultly soluble  in  ether.  It  forms  salts  and  other  compounds,  similar  to 
those  of  urea  in  constitution. 


Compound  Ureas. 

These  compounds,  which  are  exceedingly  numerous,  may  be  considered 
as  formed  by  the  substitution  of  one  or  more  alcoholic  or  acid  radicals 
for  one  or  more  of  the  remaining  hydrogen  atoms  of  urea. 

Those  containing  alcoholic  radicals  may  be  obtained,  as  urea  is  ob- 
tained from  ammonium  cyanate,  from  the  cyanate  of  the  corresponding- 
compound  ammonium;  or  by  the  action  of  ammonia,  or  of  the  compound 
ammonias,  upon  the  cyanic  ethers. 

Those  containing  acid  radicals  have  received  the  distinctive  name  of 
ureids;  some  of  them  are  of  great  interest  as  derivatives  of  uric  acid, 
which  is  itself  probably  an  ureid.  We  will  limit  our  consideration  of 
these  bodies  to  uric  acid  and  the  ureids  obtained  from  and  related  to  it. 


268  GENERAL    MEDICAL    CHEMISTRY. 


Uric  Acid— Lithic  Acid— CBH4N4O,. 

Constitution  unknown.  So  far  as  yet  known,  uric  acid  is  exclusively 
an  animal  product.  It  exists  in  the  urine  of  man  and  of  the  carnivora, 
and  in  that  of  the  herbivora  when,  during  early  life  or  starvation,  they 
are  for  the  time  being  carnivora;  as  a  constituent  of  urinary  calculi;  and 
very  abundantly  in  the  excrement  of  sejSpents,  tortoises,  birds,  molluscs, 
and  insects,  also  in  guano.  It  is  present  in  very  small  quantity  in  the 
blood  of  man,  more  abundantly  in  that  of  gouty  patients  and  in  that  of 
birds;  the  so-called  "chalk-stones"  deposited  in  the  joints  of  gouty  pa- 
tients are  composed  of  sodium  urate.  It  also  occurs  in  the  spleen,  lungs, 
liver,  pancreas,  brain,  and  muscular  fluid. 

Although  uric  acid  may  be  obtained  from  calculi,  urine,  and  guano, 
the  source  from  which  it  is  most  readily  obtained  in  a  state  of  purity  is 
the  solid  urine  of  large  serpents,  which  is  composed  almost  entirely  of 
uric  acid  and  the  acid  urates  of  sodium,  potassium,  and  ammonium.  This 
is  dried,  powdered,  and  dissolved  in  a  solution  of  potassium  hydrate,  con- 
taining one  part  of  potash  to  twenty  of  water;  the  solution  is  boiled 
until  all  odor  of  ammonia  has  disappeared.  Through  the  filtered  solution 
*a  current  of  carbon  dioxide  is  passed,  through  a  wide  tube,  until  the  pre- 
cipitate, which  was  at  first  gelatinous,  has  became  granular  and  sinks  to 
the  bottom;  the  acid  potassium  urate  so  formed  is  collected  on  a  filter, 
and  washed  with  cold-water  until  the  wash-water  becomes  turbid  when 
added  to  the  first  filtrate;  the  deposit  is  now  dissolved  in  hot  dilute 
caustic  potassa  solution,  and  the  solution  filtered  hot  into  hydrochloric 
acid  diluted  with  an  equal  volume  of  water.  The  precipitated  uric  acid 
is  washed  and  dried. 

Uric  acid,  when  pure,  crystallizes  in  small,  white,  rhombic,  rectangular 
or  hexagonal  plates,  or  in  rectangular  prisms,  or  in  dendritic  crystals  of  a 
hydrate,  C5H4N4O8,2HaO.  As  crystallized  from  urine  it  is  more  or  less 
colored  with  urinary  pigments,  and  forms  rectangular  or  rhombic  plates, 
usually  with  the  angles  rounded  so  as  to  form  lozenges,  which  are1  ar- 
ranged in  bundles,  daggers,  crosses,  or  dendritic  groups,  sometimes  of 
considerable  size.  It  is  almost  insoluble  in  water,  requiring  for  its  solu- 
tion nineteen  hundred  parts  of  boiling  water  and  fifteen  thousand  parts 
of  cold  water;  insoluble  in  alcohol  and  ether;  its  aqueous  solution  is  acid 
to  test-paper;  cold  hydrochloric  acid  dissolves  it  more  readily  than  water, 
and  on  evaporation  deposits  it  in  rectangular  plates.  It  is  tasteless  and 
odorless. 

When  heated,  uric  acid  neither  fuses  nor  sublimes,  but  is  decomposed 
with  formation  of  hydrocyanic  and  cyanuric  acids,  urea  and  ammonium 
cyanate.  When  heated  in  a  current  of  chlorine,  it  yields  cyanuric  and 
hydrochloric  acids;  when  a  current  of  chlorine  is  passed  for  some  time 
through  water  holding  uric  acid  in  suspension,  alloxan,  parabanic  and 
oxalic  acids,  and  ammonium  cyanate  are  formed;  similar  decompositions 
are  produced  by  bromine  and  iodine.  Hydrochloric  acid  simply  dissolves 
it.  Sulphuric  acid  dissolves  it;  a  hot  solution  deposits  a  deliquescent 
crystalline  compound,  C6H4N4Os,4SO4Ha;  when  heated  with  sulphuric 
acid  to  140°  for  some  time,  it  is  partly  decomposed  with  formation  of  hy- 
durilic  acid  and  pseudoxanthine.  Ozone  oxidizes  uric  acid  with  forma- 
tion of  allantoin,  carbon  dioxide,  and  urea.  The  action  of  nitric  acid 
varies  with  the  temperature;  it  dissolves  in  cold  nitric  acid  with  effer- 
vescence and  formation  of  alloxan,  alloxantine,  and  urea,  which  last  is 


'COMPOUND    UKEAS.  269 

itself  decomposed  by  the  excess  of  nitric  acid.  On  heating  the  mixture, 
or  by  oxidation  of  uric  acid  with  hot  nitric  acid,  the  alloxan  and  alloxan- 
tine  formed  are  converted  into  parabanic  acid.  A  solution  of  uric  acid 
in  nitric  acid,  treated  with  ammonium  hydrate  and  slightly  heated,  turns 
purple  from  the  formation  of  murexidoT  ammonium purpur ate  (see  p.  270). 
Solutions  of  the  alkalies  dissolve  uric  acid  with  formation  of  neutral 
urates.  Uric  acid  is  bibasic.  forming  two  series  of  salts  with  the  alkaline 
metals. 

It  is  more  convenient  to  consider  the  urates  in  this  place  than  under 
their  respective  metallic  elements. 

Ammonium  urates. — The  neutral  salt,  C5H2N4O3  (NH4)3  is  unknown. 
The  acid  salt,  CBH3N4O3  (NH4),  exists  as  a  constituent  of  the  urine  of 
the  lower  animals,  arid  occurs,  accompanying  other  urates  and  free  uric 
acid,  in  urinary  sediments  and  calculi.  Sediments  of  this  salt  are  rust- 
yellow  or  pink  in  color,  amorphous,  or  composed  of  globular  masses,  set 
with  projecting  points,  or  elongated  dumb-bells,  and  are  formed  in  alkaline 
urine.  It  is  very  sparingly  soluble  in  water  j  soluble  in  warm  hydrochloric 
acid,  from  which  solution  crystalline  plates  of  uric  acid  are  deposited. 

Potassium  urates. — The  neutral  salt,  C5H2N4O3K2,  is  obtained  when  a 
solution  of  potassium  hydrate,  free  from  carbonate,  is  saturated  with  uric 
acid;  the  solution  on  concentration  deposits  the  salt  in  fine  needles.  It 
is  soluble  in  forty-four  parts  of  cold  water  and  in  thirty-five  parts  of 
boiling  water.  It  is  alkaline  in  taste,  and  absorbs  carbon  dioxide  from 
the  air. 

The  acid  salt,  CBH3N4O3K,  is  formed  as  a  granular  (at  first  gelatinous) 
precipitate  when  a  solution  of  the  neutral  salt  is  treated  with  carbon 
dioxide.  It  dissolves  in  eight  hundred  parts  of  cold  water  and  in  eighty 
parts  of  boiling  water.  The  occurrence  of  potassium  urates  in  urinary 
sediments  and  calculi  is  very  exceptional. 

Sodium  urates. — The  neutral  salt,  C6HaN4O3Na2,  is  formed  under 
similar  conditions  as  the  corresponding  potassium  salt.  It  forms  nodular 
masses,  soluble  in  seventy-seven  parts  of  cold  water  and  in  seventy-five 
of  boiling  water  ;  it  absorbs  carbon  dioxide  from  the  air. 

The  acid  salt,  C5H3N4O3Na,  is  formed  when  the  neutral  salt  is  treated 
with  carbon  dioxide.  It  is  soluble  in  twelve  hundred  parts  of  cold 
water  and  in  one  hundred  and  twenty-five  parts  of  boiling  water.  It 
occurs  in  urinary  sediments  and  calculi,  very  rarely  crystallized.  The 
arthritic  calculi  of  gouty  patients  are  almost  exclusively  composed  of  this 
salt,  frequently  beautifully  crystallized. 

Calcium  urates. — The  neutral  salt,  C6H2N4O3Ca,  is  obtained  by  drop- 
ping a  solution  of  neutral  potassium  urate  into  a  boiling  solution  of  cal- 
cium chloride  until  the  precipitate  is  no  longer  redissolved,  and  then 
boiling  for  an  hour.  A  granular  powder,  soluble  in  fifteen  hundred 
parts  of  cold  water  and  in.  fourteen  hundred  and  forty  parts  of  boiling 
water. 

The  acid  salt,  (C5H3N4O3)aCa,  is  obtained  by  decomposing  a  boiling 
solution  of  acid  potassium  urate  with  calcium  chloride  solution.  It 
crystallizes  in  needles,  soluble  in  six  hundred  and  three  parts  of  cold 
water  and  in  two  hundred  and  seventy-six  parts  of  boiling  water.  It 
occurs  occasionally  in  urinary  sediments  and  calculi,  and  in  "  chalk 
stones." 

Lithium  urates. — The  acid  salt,  C5H3N4O3Li,  is  formed  by  dissolving 
uric  acid  in  a  warm  solution  of  lithium  carbonate.  It  crystallizes  in 
needles,  which  dissolve  in  sixty  parts  of  water  at  50°,  and  do  not  separate 


270  GENERAL   MEDICAL    CHEMISTRY. 

when  the  solution  is  cooled.  It  is  with  a  view  to  the  formation  of  this, 
the  most  soluble  of  the  urates,  that  the  compounds  of  lithium  are  given 
to  patients  suffering  with  the  uric  acid  diathesis. 

Physiology. — Uric  acid  exists  in  the  economy  chiefly  in  combination 
as  its  sodium  salts  ;  it  is  occasionally  found  free,  and  from  the  probable 
method  of  its  formation  it  is  difficult  to  understand  how  all  the  uric  acid 
in  the  economy  should  not  have  existed  there  free,  at  least  at  the 
instant  of  its  formation.  It  can  scarcely  be  doubted,  although  there  is 
no  experimental  proof  in  support  of  this  view,  that  uric  acid  is  one  of 
the  products  of  the  oxidation  of  the  albuminoid  substances — an  oxidation 
intermediate  in  the  production  of  urea  ;  and  that  consequently  diseases 
in  which  there  is  an  excessive  formation  of  uric  acid,  such  as  gout,  have 
their  origin  in  defective  oxidation. 

In  human  urine  the  quantity  of  uric  acid  varies  with  the  nature  of 
the  food  in  the  same  manner  as  does  urea,  and  about  in  the  same  pro- 
portion: 

Urea.  Uric  acid.          JSSffS^ 

Animal  food 71.5  1.25  57.2 

Mixed  food 37.0  0.76  48.7 

Vegetable  food 26.0  0.50  52.0 

Non-nitrogenized  food 16.0  0.34  47.0 

The  mean  elimination  of  uric  acid  in  the  urine  is  from  one-thirty-fifth  to 
one-sixtieth  of  that  -of  urea,  or  about  0.5  to  1.0  gram  in  twenty-four 
hours.  With  a  strictly  vegetable  diet  the  elimination  in  24  hours  may 
fall  to  0.3  grams,  and  with  a  surfeit  of  animal  food  it  may  rise  to  1.5 
grams.  The  hourly  elimination  is  increased  after  meals,  and  diminished 
by  fasting  and  by  muscular  and  mental  activity. 

Deposits  of  free  uric  acid  occur  in  acid,  concentrated  urines.  In  gout 
the  proportion  of  uric  acid  in  the  urine  is  diminished,  although,  owing  to 
the  small  quantity  of  urine  passed,  it  may  be  relatively  great;  during  the 
paroxysms  the  quantity  of  uric  acid  is  increased  both  relatively  and 
absolutely.  The  proportion  of  uric  acid  in  the  blood  is  invariably  in- 
creased in  gout. 

Tests. — Uric  acid  may  be  recognized  by  its  crystalline  form  and  by 
the  murexid  test.  To  apply  this  test  the  substance  is  moistened  with 
nitric  acid,  which  is  evaporated  nearly  to  dryness  at  a  low  temperature; 
the  cooled  residue  is  then  moistened  with  ammonium  hydrate.  If  uric 
acid  be  present,  a  yellow  residue — sometimes  pink  or  red  when  the  uric 
acid  was  abundant — remains  after  the  evaporation  of  the  nitric  acid,  and 
this,  on  the  addition  of  the  alkali,  assumes  a  rich  purplish  red  color. 

To  detect  uric  acid  in  the  blood,  about  two  drachms  of  the  serum  are 
placed  in  a  flat  glass  dish  and  faintly  acidulated  with  acetic  acid  ;  a  very 
fine  fibril  of  linen  thread  is  placed  in  the  liquid,  which  is  set  aside  and 
allowed  to  evaporate  to  the  consistency  of  a  jelly  ;  the  fibril  is  then 
removed  and  examined  microscopically.  If  the  blood  contain  uric  acid 
in  abnormal  proportion,  the  thread  will  have  attached  to  it  crystals  of 
uric  acid. 

Quantitative  determination. — The  best  method  for  the  determination 
of  the  quantity  of  uric  acid  in  urine  is  the  following  :  250  c.c.  of  the  fil- 
tered urine  are  acidulated  with  10  c.c.  of  hydrochloric  acid,  and  the  mix- 
ture set  aside  for  twenty-fours  in  a  cool  place.  A  small  filter  is  washed, 
first  with  dilute  hydrochloric  acid  and  then  with  water,  dried  at  100°,  and 
weighed.  At  the  end  of  the  twenty-four  hours  this  filter  is  moistened  in 


UREIDS    DERIVED    FROM    URIC    ACID. 


271 


a  funnel,  and  the  crystals  of  uric  acid  collected  upon  it  (those  which 
adhere  to  the  walls  of  the  precipitating  vessel  are  best  separated  by  a 
small  section  of  rubber  tubing  passed  over  the  end  of  a  glass  rod,  and 
used  as  a  brush).  No  water  is  to  be  used  in  this  part  of  the  process,  the 
filtered  urine  being  passed  through  a  second  time,  if  this  be  required,  to 
bring  all  the  crystals  upon  the  filter.  The  deposit  on  the  filter  is  now 
washed  with  35  c.c.  of  pure  water,  added  in  small  portions  at  a  time;  the 
filter  and  its  contents  are  then  dried  and  weighed.  The  difference  be- 
tween this  weight  and  that  of  the  filter  alone  is  the  weight  of  uric  acid 
in  250  c.c.  of  urine.  If  from  any  cause  more  than  35  c.c.  of  wash-water 
have  been  used,  Omgr>.  043  must  be  added  to  this  weight  for  every  c.c. 
of  extra  wash-water. 

If  the  urine  contain  albumen,  this  must  first  be  separated  by  adding 
two  or  three  drops  of  acetic  acid,  heating  to  near  100°,  until  the  coagulum 
becomes  fiocculent,  and  filtering. 


Ureids  derived  from  Uric  Acid. 

These  substances  are  quite  numerous,  and  are  divisible  into  ureids, 
diureids,  triureids,  and  uramic  acids,  according  as  they  are  formed  by  sub- 
stitution in  one,  two,  or  three  molecules  of  urea,  and  according  as  the 
acid  radical  substituted  does  or  does  not  retain  a  group  COOH.  The 
more  prominent  may  be  arranged  in  two  parallel  groups,  the  correspond- 
ing terms  of  which  differ  from  each  other  by  CO,  thus  : 


Oxalylurea 
(parabanic  acid). 


UREIDS. 

Pardbanic  series. 
C,H4N,0. 

Glyoxylurea 
(allanturic  acid). 


O.H.N.O. 

Glycolylnrea 
(hydantoin). 


C.H.NA 

Mesoxalylurea 
(alloxan). 


Alloxanic  series. 

C.H.NA 

Tartryonylurea 
(dialyuric  acid). 


O.H.N.O. 

Malonylurea 
(barbituric  acid). 


C4H.N403 

Glyoxyldiurea 
(allantoin). 


DIUREIDS. 


Oxalyl-glyoxyldiurea 
(oxalantine). 


O.H.N.O.  0,H4N.O, 


Tartronyldiurea 
(pseudo-uric  acid). 


Mesoxalyl-tartronyldiui 
(alloxantine). 


C.H.N.O, 

Hydantoic  acid. 


URAMIC  ACIDS. 
O.H.N.O. 

Oxaluric  acid. 


Alloxanic  acid. 


Some  of  these  substances  require  a  brief  mention  : 

Oxalylurea,  or  parabanic  acid,  is  urea  in  which  two  atoms  of  hydro- 
gen have  been  replaced  by  the  divalent  radical  (C.O,)"  of  oxalic  acid. 
It  is  obtained  by  the  oxidation  of  uric  acid,  or  of  alloxan  by  hot  nitric 
acid.  It  forms  six-sided  transparent  prisms,  acid  in  taste,  and  very  soluble 
in  water  and  alcohol. 


272  GENERAL   MEDICAL    CHEMISTRY. 

Glyoxyldiurea,  or  allantoin,  is,  as  its  more  common  name  implies,  ob- 
tained from  the  allantoic  fluid  of  the  cow;  it  has  also  been  found  to 
exist  in  the  urine  of  sucking1  calves,  in  that  of  dogs  and  cats  when  fed 
upon  meat,  in  that  of  children  during  the  first  eight  days  of  life,  in  that 
of  adults  after  the  ingestion  of  tannin,  and  in  that  of  pregnant  women. 

It  may  be  obtained  artificially  by  oxidizing  uric  acid  held  in  suspen- 
sion in  boiling  water,  with  pure  oxide  of  lead. 

It  crystallizes  in  small,  od'orless,  tasteless,  colorless,  neutral  and  trans- 
parent prisms;  sparingly  soluble  in  cold  water,  readily  in  warm  water, 
alcohol,  and  ether.  When  heated  with  alkalies  it  yields  oxalic  acid  and 
ammonia;  with  dilute  acids,  allanturic  acid"  and  with  oxidizing  agents, 
urea  and  allantoic  acid. 

It  is  probably,  like  uric  acid,  an  intermediate  product  of  the  oxidation 
of  the  albuminoids. 

Mesoxalylurea,  or  alloxan,  is  a  product  of  the  limited  oxidation  of  uric 
acid.  It  has  been  found  in  one  instance  in  the  intestinal  mucus,  in  a  case 
of  diarrhoaa,  and.  probably  in  the  urine  in  a  case  of  heart  disease. 

It  forms  colorless  crystals,  readily  soluble  in  water.  Wlien  exposed 
to  the  air  it  gradually  turns  red,  which  color  it  communicates  to  the  skin 
on  contact  with  it. 

Oxaluric  acid  occurs,  as  its  ammonium  salt,  as  a  normal  constituent, 
in  small  but  constant  quantity,  of  human  urine,  from  which  it  can  only 
be  obtained  by  operating  upon  large  quantities.  It  may  also  be  obtained 
by  heating  parabanic  acid  with  calcium  carbonate. 

It  forms  a  white,  sparingly  soluble  powder,  which,  on  boiling  with 
water  or  with  the  alkalies,  is  converted  into  urea  and  oxalic  acid.  The 
ammonium  salt  crystallizes  in  white,  glistening  needles,  sparingly  soluble 
in  water. 

Its  ready  conversion  into  urea  and  oxalic  acid,  and  its  formation  from 
parabanic  acid,  itself  a  product  of  oxidation  of  uric  acid,  shows  it  to  be 
one  of  the  numerous  terms  in  the  oxidation  of  the  nitrogenous  constitu- 
ents of  the  body. 


Substances  of  Unknown  Constitution  Related  to  Uric  Acid. 

There  exist  several  substances,  of  unknown  constitution,  which,  from 
their  products  of  decomposition  and  their  occurrence,  seem  to  be  closely 
related  to  uric  acid;  some  of  these  occur  in  the  animal  economy:  xanthine, 
hypo^anthine,  guanine,  carnine. 


Xanthine,  C6H4N4O3. 

Sometimes  called  xanthic  oxide  or  urous  acid,  was  first  discovered  as 
a  constituent  of  a  rare  form  of  urinary  calculus;  since  that  time  it  has 
been  found  to  exist  in  small  quantity  in  the  pancreas,  spleen,  liver,  thy- 
mus  and  brain  of  mammals  and  fishes;  also  in  human  urine  after  the  use  of 
sulphur  baths  and  inunctions. 

When  dry  it  forms  an  amorphous,  yellowish  white  powder;  very  spar- 
ingly soluble  in  cold  water,  rather  more  freely  in  hot  water.  If  dissolved 
in  nitric  acid  and  the  solution  evaporated  by  heat,  xanthine  leaves  a  yel- 
low residue,  which  assumes  a  reddish  yellow  color  on  contact  with  potas- 
sium hydrate  solution,  and  this  when  heated  turns  violet-red. 


CAKNINE.  273 

Xanthine  calculi  are  of  very  infrequent  occurrence;  they  vary  in  size 
from  that  of  a  pea  to  that  of  a  pigeon's  egg;  are  rather  hard,  brownish 
yellow,  smooth,  shining,  and  made  up  of  well-defined,  concentric  layers; 
their  broken  surface  assumes  a  waxy  polish  when  rubbed. 


Hypoxanthine — Sarcine — C6H4N40, 

was  discovered  in  the  spleen;  it  has  also  been  found  to  exist  in  the 
muscular  tissue  of  mammals,  in  the  thymus,  suprarenal  capsules,  and 
brain;  in  the  human  liver  in  acute  yellow  atrophy;  and  in  the  blood  and 
urine,  accompanied  by  xanthine,  in  leucocythaemia;  and  probaby  iri  small 
quantity  in  healthy  blood;  and  in  the  marrow  of  bones. 

It  is  best  obtained  from  the  mother-liquor  of  the  preparation  of  crea- 
tine  (q.  v.)>  this  is  diluted  with  water,  rendered  alkaline  with  ammonium 
hydrate,  and  treated  with  silver  nitrate  in  ammonical  solution;  the  pre- 
cipitate is  washed  with  dilute  ammonia  by  decantation,  collected  on  a  filter, 
and  extracted  with  boiling  nitric  acid;  sp.  gr.  1.1;  the  nitric  acid  solution, 
on  cooling,  deposits  a  compound  of  silver  nitrate  and  hypoxanthine;  this  is 
suspended  in  water,  decomposed  by  hydrogen  sulphide;  the  filtered  solu- 
tion on  concentration  deposits  crystals  of  hypoxanthine  nitrate. 

Free  hypoxanthine,  obtained  from  the  nitrate  by  decomposition  with 
ammonium  hydrate,  forms  nodular  masses,  never  crystals;  soluble  in 
three  hundred  parts  cold  and  seventy-eight  parts  boiling  water,  sparingly 
soluble  in  alcohol,  readily  in  dilute  acids  and  alkalies,  with  which  and 
with  metallic  salts  it  forms  compounds.  It  may  be  obtained  from  uric 
acid  or  xanthine  by  the  action  of  sodium  amalgam,  and  when  oxidized 
with  nitric  acid  it  yields  xanthine.  The  close  relationship  of  these  bodies 
is  shown  by  the  formulae: 


Uric  acid C5H4N4Oa 

Xanthine C5H4N4Oa 

Hypoxanthine C5H4N4O 


The  flesh  of  the  ox  contains  0.022  per  cent,  of  hypoxanthine;  that  of 
the  rabbit  0.026  per  cent.;  leucocythsemic  blood  0.0075  per  cent. 


Guanine,  C&H6N5O, 

as  its  name  implies,  was  first  obtained  from  guano;  it  has  also  been 
found  in  the  pancreas,  lungs  and  liver  of  certain  mammalians,  and  in  the 
excrements  of  the  lower  orders. 

It  appears  as  a  white  or  yellowish  amorphous  mass;  odorless  and 
tasteless;  almost  insoluble  in  water,  alcohol  and  ether;  readily  in  acids 
and  alkalies,  with  which  it  forms  compounds. 


Gamine,  C7H8N4Os-f  H2O, 

has  been  obtained  from  Liebig's  meat  extract.     It  forms  chalky,  micro- 
scopic crystals;  sparingly  soluble  in  cold,  readily  in  warm  water;  insoluble 
in  alcohol  and  ether.     Forms  compounds  with  acids  and  alkalies  similar 
to  those  of  hypoxanthine. 
18 


274  GENERAL    MEDICAL    CHEMISTRY. 


COOH 

Carbamic  Acid.   I  , 

NH2 

has  not  been  isolated,  and  is  only  known  in  combination  as  its  ammonium 
salt  and  in  its  ethers;  the  latter  are  known  under  the  generic  name  of 
urethanes.  Its  ammonium  salt  exists  in  sesquicarbonate  of  ammonium 
(q.  v.),  and  has  been  said  to  exist  in  blood-serum  (see  p.  256). 

The  remaining  acids  of  this  series,  being  monobasic,  each  forms   a 
single  amide.     None  of  these  amides  are  of  other  than  theoretic  interest. 


Amides  of  the  Acid  Series,  CnH2n_9O4. 

CO-NH2 

Oxamide,    |  ,  was  one  of  the  first  of  this  class  of  substances 

CO-NH, 

obtained.  It  is  formed  by  depriving  ammonium  oxalate  of  the  elements 
of  two  molecules  of  water,  or  by  the  action  of  ammonia  upon  ethyl  oxa- 
late. 

It  forms  a  light,  white,  crystalline  powder;  odorless,  tasteless,  and 
neutral;  almost  insoluble  in  cold  water,  sparingly  soluble  in  warm  water. 
It  is  decomposed  by  sulphuric  ac*id  into  the  two  oxides  of  carbon  and 
ammonium  sulphate;  by  phosphoric  anhydride  into  water  and  cyanogen; 
by  mercuric  oxide  into  urea  and  carbon  dioxide;  and  by  acids  arid  alka- 
lies into  oxalic  acid  and  ammonia. 

Corresponding  to  it  there  exist  a  number  of  substances  constituted  by 
the  substitution  of  alcoholic  radicals  for  the  remaining  hydrogen  atoms, 
and  consequently  comparable  to  the  ureids. 
CO-NH, 

Oxamic  acid.  I  ,  is  formed  by  the  dry  distillation  of  ammo- 

CO,OH 

nium  oxalate  at  220° — 230°.  It  appears  as  a  fine,  colorless  powder;  spar- 
ingly soluble  in  water  and  alcohol;  insoluble  in  ether;  fusible  at  173°. 

The  remaining  acids  of  this  series  are  capable  of  forming  compounds 
similar  to  the  above,  none  of  which,  however,  require  further  notice. 


TRIATOMIC  ALCOHOLS. 

There  is  as  yet  only  one  alcohol  known  containing  a  trivalent  radical. 
This  is  glycerin,  whose  relation  to  the  monoatomic  and  diatomic  alcohols 
is  shown  by  the  following  formulae: 

Propane.  Propyl  alcohol.  Propyl  glycol.  Glycerin. 

CH,      CH,         CH,OH      CH,OH 
CH,      CH,         CH,        CHOH 
CH,      CH3OH      CH,OH      CH.OH 


GLYCERIN. 


275 


Glycerin,  CHS  (OH),, 

was  first  obtained  as  a  secondary  product  in  the  manufacture  of  lead 
plaster;  it  is  now  produced  as  a  by-product  in  the  manufacture  of  soaps 
and  of  stearin  candles.  It  exists  free  in  palm-oil  and  in  other  vegetable 
oils;  it  is  produced  in  small  quantity  during  alcoholic  fermentation,  and 
is  consequently  present  in  wine  and  beer.  It  is  much  more  widely  dis- 
seminated in  its  ethers,  the  neutral  fats,  in  the  animal  and  vegetable 
kingdoms. 

It  has  been  obtained  by  partial  synthesis,  by  heating  for  some  time  a 
mixture  of  allyl  tribromide,  silver  acetate  and  acetic  acid,  and  saponify- 
ing the  triacetin  so  obtained. 

The  glycerin  obtained  by  the  process  now  generally  followed — the 
decomposition  of  the  neutral  fats  and  distillation  of  the  products  in  a 
current  of  superheated  steam — is  free  from  the  impurities  which  contami- 
nated the  products  of  the  older  processes.  The  only  impurity  likely  to  be 
present  is  water,  which  may  be  recognized  by  the  low  specific  gravity  of 
the  mixture. 

Glycerin  is  a  colorless,  odorless,  syrupy  liquid;  has  a  sweetish  taste; 
sp.  gr.  1.26  at  15°.  Although  it  cannot  usually  be  caused  to  crystallize 
by  the  application  of  the  most  intense  cold,  it  does  so  sometimes  under 
imperfectly  understood  conditions,  forming  small  white  needles  of  sp.  gr. 
1.268,  and  fusible  between  7°  and  8°;  it  is  soluble  in  all  proportions  in 
water  and  alcohol,  insoluble  in  ether  and  in  chloroform.  The  specific 
gravity  of  mixtures  of  glycerin  and  water  are: 


Per  cent, 
glycerin. 

Specific  gravity. 

Per  cent, 
glycerin. 

Specific  gravity. 

Per  cent, 
glycerin. 

Specific  gravity. 

10 

1.024 

40 

1.105 

70 

1.170 

20 

1.051 

50 

1.127 

80 

1.220 

30 

1.075 

60 

1.159 

90 

1.232 

Glycerin  is  a  solvent  of  a  great  number  of  mineral  and  organic  sub- 
stances; 100  parts  of  glycerin  dissolve: 


Sodium  carbonate. 


Parts. 

.  98. 0  Ammonium  chloride 


Borax 60.0  Sodium  chloride 20.0 

Tannin 50.0  Arsenious  acid 2  >.0 


Urea 50.0  Arsenic  acid. 

Potassium  arsenate  . . .  50.0  Ammonium  carbonate. 


Sodium  arsenate 50.0 

Zinc  chloride 50.0 

Potassium  iodide. ...    .  40.0 


Zinc  iodide 40.0  Oxalic  acid 


Alum .  40.0 


Zinc  sulphate 35.0  Boric  acid 


Potassium  bromide  . . .  25.0  Mercuric  chloride 

Ferrous  sulphate 25.0  Cinchonine  sulphate  . . 


Parts. 
.  20.0 


20.0 
20.0 


Lead  acetate 20.0 

Morphine  chloride 20.0 

Ferric  lactate  . .  .   16.0 


15.0 


Barium  chloride ..       .10.0 


10.0 


Atropine  sulphate  ....  33. 0  Benzoic  acid 10. 0 

Potassium  cyanide 32.0  Calcic  sulphide 10.0 

Cupric  sulphate 30.0  Potassium  sulphide. . .  10.0 

Mercuric  cyanide 27.0  Sodium  bicarbonate  . .  8.0 


7.5 
6.7 
Strychnine  sulphate  . .  22. 5  Tartar  emetic  .* 5.5 


ParfK. 

3.85 

Potassium  chlorate  . .     3.5 
Atropine 3.0 


Strychnine  nitrate. . . 


Quinine  sulphate 


2.75 


Brucine 2.25 

Iodine 1.9 

Veratrine 1.0 

Quinine  tannate 0.77 

Quinine 0.5 

Cinchonine 0.5 

Morphine 0. 45 

Mercuric  iodide 0.29 

Strychnine 0.25 

Phosphorus 0.20 

Sulphur 0.10 


Sugar 
Gum 


40.0 
28.5 


276  GENERAL    MEDICAL   CHEMISTRY. 

The  following  substances  are  soluble  in  glycerin  in  all  proportions  : 


Bromine. 
Ferrous  iodide. 
Antimony  trichloride. 
Ferric  chloride. 
Sodium  hypochlorite. 
Potassium  hypochlorite. 
Sulphuric  acid. 


Nitric  acid. 
Hydrochloric  acid. 
Phosphoric  acid. 
Acetic  acid. 
Tartaric  acid. 
Citric  acid. 
Laetic  acid. 


Ammonia. 
Potassium  hydrate. 
Sodium  hydrate. 
Codeine. 
Silver  nitrate. 
Mercurous  nitrate. 


- 


When  glycerin  is  heated,  a  portion  distils  unaltered  between  275° — 
280°;  the  greater  part,  however,  is  decomposed,  giving  off  acrolein,  acetic 
acid,  carbon  dioxide,  and  combustible  gases.  It  may  be  distilled  without 
decomposition  in  a  current  of  superheated  steam,  the  temperature  being 
maintained  between  288° — 315°. 

Platinum  black  oxidizes  glycerin  with  the  production,  finally,  of  water 
and  carbon  dioxide;  oxidized  by  manganese  dioxide  and  sulphuric  acid, 
it  yields  carbon  dioxide  and  formic  acid.  The  action  of  nitric  acid  on 
glycerin  varies  with  the  conditions;  if  a  layer  of  glycerin,  diluted  with 
water,  is  floated  on  nitric  acid  of  sp.  gr.  1.5,  glyceric  acid  is  formed;  by 
the  action  of  a  mixture  of  concentrated  nitric  and  sulphuric  acids  on 
glycerin,  nitro-glycerin  (q.  v.)  is  formed. 

When  heated  with  an  alkaline  hydrate,  it  forms  a  mixture  of  potas- 
sium formiate  and  acetate.  Phosphoric  anhydride  removes  from  it  the 
elements  of  water,  to  form  acrolein  (q.  v.);  the  same  change  is  produced 
when  glycerin  is  heated  with  sulphuric  acid  or  with  potassium  hydro- 
sulphate.  When  heated  with  oxalic  acid,  it  is  decomposed  into  carbon 
dioxide  and  formic  acid. 

Uses. — Glycerin  is  very  extensively  used  in  the  arts  and  in  medicine. 
Being  unctuous  to  the  touch,  and  neither  volatile  nor  prone  to  become 
gummy,  it  is  used  to  protect  substances  from  contact  with  air;  its  non- 
volatility  and  power  of  attracting  moisture  from  the  air  renders  it  invalu- 
able for  maintaining  the  moisture  of  certain  bodies,  as  modeller's. clay,  dye- 
stuffs,  etc.  It  is  also  largely  used  in  weaving,  dyeing,  calico-printing, 
printing;  to  prevent  mouldiness  in  various  substances;  as  a  solvent;  in 
the  manufacture  of  nitro-glycerin,  dynamite,  etc. 

Its  neutrality,  unctuousness,  and  non-volatility  render  it  applicable  to 
many  pharmaceutical  uses.  As  a  solvent,  in  the  preparation  of  glycerolcs, 
and  of  semi-solid  cerates,  glycerates;  for  the  prevention  of  mould  in  solu- 
tions of  morphia,  etc.,  etc. 

The  glycerin  used  for  medicinal  purposes  should  respond  to  the  fol- 
lowing tests:  1st,  its  specific  gravity  should  not  vary  much  from  that 
given  above;  2d,  it  should  not  rotate  polarized  light;  3d,  it  should  not 
turn  brown  when  heated  with  sodium  hydrate;  4th,  it  should  not  be  col- 
ored by  hydrogen  sulphide;  5th,  when  dissolved  in  its  own  weight  of 
alcohol  containing  one  per  cent,  of  sulphuric  acid,  the  solution  should  be 
clear;  6th,  when  mixed  with  an  equal  volume  of  sulphuric  acid  of  sp. 
gr.  1.83,  it  should  form  a  limpid,  brownish  mixture,  but  should  not  give 
off  gas. 


Malic  Acid,  C4H6O6. 

This  acid  is  the  only  one  of  those  derivable  from  the  glycerin  series 
which  is  of  medical  importance.  It  exists  in  the  vegetable  kingdom, 
either  free  or  in  combination  with  potassium,  sodium,  calcium,  magnesium, 


ETHERS    OP    GLYCERIN.  277 

or  organic  bases;  principally  in  fruits  such  as  apples,  cherries,  etc.;  ac- 
companied by  citrates  and  tartrates. 

It  may  be  obtained  from  the  unripe  berries  of  the  mountain  ash.  The 
expressed  juice  is  heated  and  calcium  carbonate  added  as  long  as  there  is 
effervescence;  the  liquid  is  allowed  to  cool,  filtered,  plumbic  nitrate  added, 
and  set  aside  until  the  plumbic  nitrate  crystallizes.  The  crystals  are 
slightly  washed  with  cold  water,  dissolved,  the  solution  decomposed  with 
hydrogen  sulphide,  filtered,  and  the  filtrate  evaporated  over  the  water- 
bath. 

The  acid  obtained  by  this  process  crystallizes  in  brilliant,  prismatic 
needles;  odorless;  having  a  strongly  acid  taste;  fusible  at  100°;  lose 
water  at  140°;  deliquescent,  very  soluble  in  water  and  in  alcohol.  Its 
aqueous  solution  is  laevogyrous:  [a]  D= — 5°.  When  heated  to  175° — 180° 
malic  acid  is  decomposed  into  water  and  maleic  acid. 

There  exists  another  modification  of  malic  acid,  formed  by  the  action 
of  nitrous  acid  upon  aspartic  acid,  which  differs  from  this  in  being  opti- 
cally inactive,  in  its  fusing-point,  133°,  and  in  the  properties  of  its  salts. 

COOH 

CHOH 

As  indicated  by  the  formula  of  constitution    I  ,  malic    acid    is 

H. 

COOH 

triatomic  and  dibasic. 

The  malates  when  taken  into  the  economy,  are  oxidized  to  carbonates. 


ETHERS  OP  GLYCERIN. 

GLYCERIDES. 

Being  a  triatomic  alcohol,  glycerin  contains  three  groups  OH,  the  hy- 
drogen of  each  of  which  may  be  replaced  by  an  acid  radical;  or,  more 
properly  speaking,  one,  two,  or  three  of  these  oxhydryl  groups  may  be  re- 
moved, leaving  a  univalent,  divalent,  or  trivalent  remainder,  which  may 
replace  the  hydrogen  of  one,  two,  or  three  molecules  of  a  monobasic  acid 
to  form  three  series  of  ethers: 

CHaOH        CHa-O-CaH3O        CH3-O-C3H3O        CHa-  0-CaH80 
CHOH         CHOH  CH-O-CaH80         6H-0-CaH3O 

CHaOH        CHaOH  CHaOH  CHa-0-CaH90 

Glycerin.  Manoactin.  Diacetin.  Triacetin. 

Of  the  many  substances  of  this  class,  only  a  few,  principally  those  en- 
tering into  the  composition  of  the  neutral  fats,  require  consideration  here. 

Tributyrin,  C3H3  (0,C4H70)3— exists  in  butter.  It  may  also  be  ob- 
tained by  heating  glycerin  with  butyric  and  sulphuric  acids.  It  is  a 
liquid,  having  a  pungent  odor  and  taste;  is  exceedingly  prone  to  decom- 
position, with  liberation  of  butyric  acid. 


278  GENERAL    MEDICAL    CHEMISTRY. 

Trivalerin,  C3H5  (0,C6H90)3 — exists  in  the  oil  of  some  maritime 
mammalia,  and  is  identical  with  the  phocenine  of  Chevreul. 

Tricaproin,  C3H5  (0,CaH110),~ Tricaprylin,  C3HB  (O.C.H  .0),;  and 
Tricaprin,  C3H5  (0,C10HJ9O)3 — exist  in  small  quantities  in  milk,  butter 
and  cocoa-butter. 

Tripalmitin,  C3H5  (O,C16H31O)3 — exists  in  most  animal  and  vegetable 
fats,  notably  in  palm-oil  ;  it  may  also  be  obtained  by  heating  glycerin 
with  eight  to  ten  times  its  weight  of  palmitic  acid  for  eight  hours  at  250°. 
It  forms  crystalline  plates,  very  sparingly  soluble  in  alcohol,  even  when 
boiling;  very  soluble  in  ether.  It  fuses  at  50°  and  solidifies  again  at 
46°. 

Trimargarin,  C3H6  (O,C17H33O)3 — has  probably  been  obtained  arti- 
ficially as  a  crystalline  solid,  fusible  at  60°,  solidifiable  at  52°.  The  sub- 
stance formerly  described  under  this  name  as  a  constituent  of  animal  fats 
is  a  mixture  of  tripalmitin  and  tristearin. 

Tristearin,  C3H6  (O,C18H36O)3— is  the  most  abundant  constituent 
of  the  solid  fatty  substances.  It  is  prepared  in  large  quantities  as  an 
industrial  product  in  the  manufacture  of  stearin  candles,  etc.,  but  is  ob- 
tained in  a  state  of  purity  only  with  great  difficulty. 

In  as  pure  a  form  as  readily  obtainable,  it  forms  a  hard,  brittle,  crystal- 
line mass  ;  fusible  at  68°,  solidifiable  at  61°;  soluble  in  boiling  alcohol,  al- 
most insoluble  in  cold  alcohol,  readily  soluble  in  ether. 

Triolein,  C8H?  (O,C18H33O)3 — exists  in  varying  quantity  in  all  fats, 
and  is  the  predominant  constituent  of  those  which  are  liquid  at  ordinary 
temperatures,  it  may  be  obtained  from  animal  fats  by  boiling  with  alcohol, 
filtering  the  solution,  decanting  after  twenty-four  hours'  standing;  freez- 
ing at  0°,  and  expressing. 

It  is  a  colorless,  odorless,  tasteless  oil  ;  soluble  in  alcohol  and  ether, 
insoluble  in  water;  sp.  gr.  0.92. 

Trinitro-glycerin  —  nitro-glycerin  —  C3H5  (ONO2)3.  —  This  sub- 
stance, which  is  used  as  an  explosive,  both  pure  and  mixed  with  other 
substances  in  dynamite,  giant  powder,  etc.,  is  obtained  by  the  combined 
action  of  sulphuric  and  nitric  acids  upon  glycerin.  Fuming  nitric  acid  is 
mixed  with  twice  its  weight  of  sulphuric  acid  in  a  cooled  earthen  vessel; 
thirty-three  parts  by  weight  of  the  mixed  acids  are  placed  in  a  porcelain 
vessel,  and  five  parts  of  glycerin,  of  31°  Beaume,  are  gradually  added 
with  constant  stirring,  while  the  vessel  is  kept  well  cooled  ;  after  five 
minutes  the  whole  is  thrown  into  five  to  six  volumes  of  cold  water;  the 
nitro-glycerin  separates  as  a  heavy  oil  which  is  washed  with  cold  water. 

Nitro-glycerin  is  an  odorless,  yellowish  oil  ;  has  a  sweetish  taste;  sp. 
gr.  1.6;  insoluble  in  water,  soluble  in  alcohol  and  ether;  not  volatile  ; 
crystallizes  in  prismatic  needles  when  kept  for  some  time  at  0°;  fuses 
again  at  8°. 

When  pure  nitre-glycerin  is  exposed  to  the  air  at  30°  for  some  time, 
it  decomposes  without  explosion  and  with  production  of  glyceric  and 
oxalic  acids.  When  heated  to  100°  it  volatilizes  without  decomposition; 
at  185°  it  boils,  giving  off  nitrous  fumes;  at  217°  it  explodes  violently;  if 
quickly  heated  to  257°,  it  assumes  the  spheroidal  form  and  volatilizes  with- 
out explosion.  Upon  the  approach  of  flame  at  low  temperatures  it  ig- 
nites and  burns  with  slight  decrepitations.  When  subjected  to  sudden 
shock,  it  is  suddenly  decomposed  into  carbon  dioxide,  nitrogen,  vapor  of 
water  and  oxygen,  the  decomposition  being  attended  with  a  violent  ex- 
plosion. 

In  order  to  render  this  explosive  less  dangerous  to  handle,  it  is  now 


FIXED    VEGETABLE    OILS.  279 

usually  mixed  with  some  inert  substance,  usually  diatomaceous  earth,  in 
which  form  it  is  known  as  dynamite,  etc. 

When  taken  internally,  nitro-glvcerin  is  an  active  poison,  producing* 
effects  somewhat  similar  to  those  of  strychnine  ;  even  in  drop-doses,  di- 
luted, it  causes  violent  headache,  fever,  intestinal  pain,  and  nervous  symp- 
toms. It  has  been  latterly  used  as  a  therapeutic  agent,  and  has  been 
used  by  the  homoeopaths  under  the  name  of  glonoin. 


NEUTRAL  OILS  AND  FATS. 

These  are  mixtures  in  varying  proportions  of  tripalmitin,  tristearin, 
and  triolein,  with  small  quantities  of  other  glycerides,  coloring  and  odor- 
ous principles,  which  are  obtained  from  animal  and  vegetable  bodies. 
The  oils  are  fluid  at  ordinary  temperatures,  the  solid  glycerides  being  in 
solution  in  an  excess  of  the  liquid  triolein.  The  fats,  owing  to  a  less  pro- 
portion of  the  liquid  glyceride,  are  solid  or  semi-solid  at  the  ordinary  tem- 
perature of  the  air;  members  of  both  classes  are  fluid  at  sufficiently  high 
temperatures,  and  solidify  when  exposed  to  a  sufficiently  low  temperature. 
They  are,  when  pure,  nearly  tasteless  and  odorless,  unctuous  to  the  touch, 
insoluble  in  and  not  miscible  with  water,  upon  which  they  float;  combus- 
tible, burning  with  a  luminous  flame;  when  rubbed  upon  paper  they  ren- 
der it  translucent.  When  heated  with  the  caustic  alkalies  or  in  a  current 
of  superheated  steam,  they  are  saponified,  i.  e.,  decomposed  into  glycerin 
and  a  fatty  acid.  If  the  saponification  be  produced  by  an  alkali,  the 
fatty  acid  combines  with  the  alkaline  metal  to  form  a  soap  (q.  v.). 

Most  of  the  fats  and  many  of  the  oils,  when  exposed  to  the  air,  absorb 
oxygen,  are  decomposed  with  liberation  of  volatile,  fatty  acids,  and  ac- 
quire an  acid  taste  and  odor,  and  an  acid  reaction.  A  fat  which  has 
undergone  these  changes  is  said  to  have  become  rancid.  Many  of  the 
vegetable  oils  are,  however,  not  prone  to  this  decomposition.  Some  of 
them,  by  oxidation  on  contact  with  the  air,  become  thick,  hard  and  dry, 
forming  a  kind  of  varnish  over  surfaces  upon  which  they  are  spread; 
these  are  designated  as  drying  or  siccative  oils.  Others,  although  they 
become  more  dense  on  exposure  to  air,  become  neither  dry  nor  gummy; 
these  are  known  as  non-drying,  greasy,  or  lubricating  oils. 

Under  ordinary  conditions,  oils  and  melted  fats  do  not  mix  with 
water,  and,  if  shaken  with  that  fluid,  form  a  temporary  milky  mixture, 
which,  on  standing  for  a  short  time,  separates  into  two  distinct  layers, 
the  oil  floating  on  the  water.  In  the  presence,  however,  of  small  quanti- 
ties of  certain  substances,  such  as  albumen,  pancreatin  (g.  v.),  ptvalin, 
etc.,  the  milky  mixture  obtained  by  shaking  together  oil  and  water  does 
not  separate  into  distinct  layers  on  standing;  such  a  mixture,  in  which 
the  fat  is  held  in  a,  permanent  state  of  suspension  in  small  globules  in  a 
watery  fluid,  is  called  an  emulsion. 


Fixed  Vegetable  Oils. 

These  substances  are  designated  as  "  fixed,"  to  distinguish  tnem  from 
other  vegetable  products  having  an  oily  appearance,  but  which  differ  from 
the  true  oils  in  their  chemical  composition  and  in  their  physical  proper- 
ties, especially  in  that  they  are  volatile  without  decomposition,  and  are 


280  GENERAL    MEDICAL    CHEMISTRY. 

obtained  by  distillation,  while  the  fixed  oils  are  obtained  by  expression, 
with  or  without  the  aid  of  a  moderate  heat.  The  fixed  oils  form  two  classes, 
the  greasy  and  drying  oils  (see  above). 

In  testing  the  purity  of  the  oils,  advantage  is  taken  of  the  specific 
gravity,  point  of  congelation,  and  of  the  action  of  reagents:  1st,  sulphuric 
acid — about  twenty  drops  of  the  oil  are  placed  on  a  watch-glass  over  a 
white  surface,  and  a  drop  of  concentrated  sulphuric  acid  is  added;  after- 
ward the  whole  is  stirred  with  a  glass  rod;  the  changes  of  color  observed 
with  the  principal  oils  before  and  after  stirring  vary  with  the  different 
oils.  2d,  Pouters  reagent,  made  by  dissolving  six  parts  of  mercury  in 
7.5  parts  of  nitric  acid  of  36°  in  the  cold.  One  part  of  this  reagent  is 
well  shaken  with  twelve  parts  of  the  oil,  and  the  mixture  set  aside  for 
twelve  hours;  the  greasy  oils  are  completely  solidified,  while  the  drying 
oils  remain  fluid.  3d,  Ifaitchecorne's  reagent — three  parts  of  nitric  acid 
of  40°,  diluted  with  one  part  of  distilled  water;  one  gram  of  this  reagent 
is  mixed  with  three  grams  of  the  oil  and  shaken  in  a  test-tube. 

Palm-oil  is  the  product  of  a  species  of  palm  growing  on  the  Guinea 
coast,  in  the  West  Indies,  and  South  America.  It  is  a  reddish  yellow 
solid  at  ordinary  temperatures,  has  a  bland  taste  and  an  aromatic  odor. 
It  saponifies  readily,  and  is  used  in  the  manufacture  of  palm-soap.  It  is 
usually  acid,  and  contains  free  glycerin  from  spontaneous  decomposition. 

Rape-seed  oil  and  colza-oil  are  produced  from  the  seeds  of  various 
species  of  Brassica  /  yellow,  limpid  oils,  having  a  strong  odor  and  a 
disagreeable  taste.  They  are  used  for  burning  in  lamps  and  for  the 
manufacture  of  soft-soaps. 

Croton-oil — Oleum  tiglii  (U.  S.) — Oleum  crotonis  (Br.) — is  one  of  the 
few  fixed  oils  possessed  of  distinct  medicinal  properties.  It  varies  much 
in  color  and  activity,  according  to  its  source;  that  which  is  obtained  from 
the  East  is  yellowish,  liquid,  transparent,  and  much  less  active  than  that 
prepared  in  Europe  from  the  imported  seeds,  which  is  darker,  less  fluid, 
caustic  in  taste,  and  wholly  soluble  in  absolute  alcohol.  Croton-oil  con- 
tains, besides  the  glycerides  of  oleic,  crotonic  and  fatty  acids,  about  four 
per  cent,  of  a  peculiar  principle  called  by  Schlippe  crotonol,  to  which  the 
oil  owes  its  vesicating  properties;  it  also  contains  an  alkaloid-like  sub- 
stance, also  existing  in  castor-oil,  called  ricinine.  None  of  these  bodies, 
however,  are  possessed  of  the  drastic  powers  of  the  oil  itself. 

Peanut-oil — Ground-nut  oil — an  almost  colorless  oil,  very  much  re- 
sembling olive-oil,  in  place  of  which  it  is  frequently  used  for  culinary  pur- 
poses, intentionally  or  otherwise.  It  is  readily  saponifiable,  yielding  two 
peculiar  acids,  arachaic  and  Jiypogdlc  (see  Olive-oil). 

Cocoanut-oil  or  butter,  not  to  be  confounded  with  cocoa-butter,  is  at 
ordinary  temperatures  a  white  solid  resembling  lard;  fuses  at  about  20°, 
and  solidifies  at  about  10°;  it  has  a  pleasant  odor  and  a  bland  taste.  It 
is  readily  saponifiable,  yielding  a  hard  sodium  soap.  It  easily  becomes 
rancid.  It  is  said  to  contain  an  acid,  called  cocinic,  or  cocostearic. 

Almond-oil —  Oleum  amygdalae  dulcis  (U.  S.)—  Oleum  amygdalae  (Br.) 
— a  light  yellow  oil,  very  soluble  in  ether,  soluble  in  twenty-four  parts  of 
alcohol;  nearly  inodorous;  has  a  bland,  sweetish  taste.  It  is  largely  used 
in  pharmacy,  in  the  preparation  of  ointments,  and  in  the  arts  in  soap 
manufacture.  The  pure  oil  has  no  odor  of  bitter  almonds;  is  completely 
solidified  by  Pontet's  reagent;  is  colored  peach-red,  but  not  green,  by  a 
mixture  of  nitric  and  sulphuric  acids;  produces  no  coloration  when  its 
ethereal  solution  is  shaken  with  a  concentrated  alcoholic  solution  of  silver 
nitrate,  and  the  mixture  set  aside  in  the  dark  for  twelve  hours. 


ANIMAL    OILS.  281 

Olive-oil — Oleum  olivoe  (U.  S.,  Br.)— a  well-known  oil  of  a  yellow  or 
greenish  yellow  color,  almost  odorless,  and  of  a  bland  and  sweetish  taste. 
The  finest  grades  have  a  yellow  tinge  and  a  faint  taste  of  the  fruit;  they 
are  prepared  by  cold  pressure;  they  are  less  subject  to  rancidity  than  the 
lower  grades.  Olive-oil  is  very  frequently  adulterated,  chiefly  with  poppy- 
oil,  sesame-oil  and  peanut-oil;  the  presence  of  the  first  is  detected  by 
Pontet's  reagent,  which  converts  pure  olive-oil  into  a  solid  mass,  while  an 
oil  adulterated  with  a  drying  oil  remains  semi-solid.  A  contamination 
with  oil  of  sesame  is  indicated  by  the  production  of  a  green  color,  with  a 
mixture  of  nitric  and  sulphuric  acids.  Peanut-oil,  an  exceedingly  common 
adulterant  in  this  country,  is  recognized  by  the  point  of  congelation,  or 
more  delicately  by  the  following  method:  ten  grams  of  the  oil  are 
saponified;  the  soap  is  decomposed  with  hydrochloric  acid;  the  liberated 
fatty  acids  dissolved  in  50  c.c.  of  strong  alcohol;  the  solution  precipitated 
with  lead  acetate;  the  precipitate  washed  with  ether;  the  residue  decom- 
posed with  hot  dilute  hydrochloric  acid;  the  oily  layer  separated  and 
extracted  with  strong  alcohol;  the  alcoholic  fluid,  on  evaporation,  yields 
crystals  of  arachdic  acid,  if  the  oil  contains  peanut-oil. 

Cotton-seed  oil  is  also  added  to  olive-oil  in  this  country  ;  its  presence 
is  detected,  like  that  of  other  drying  oils,  by  the  formation  of  a  pasty 
magma  in  place  of  a  solid  mass  when  the  oil  is  subjected  to  the  action  of 
Pontet's  reagent. 

Cocoa-butter — Oleum  theobromce  (U.  S.,  Br.) — is  at  ordinary  tempera- 
tures a  whitish  or  yellowish  solid  of  the  consistency  of  tallow,  and  hav- 
ing an  odor  of  chocolate  and  a  pleasant  taste;  it  does  not  easily  become 
rancid.  The  most  reliable  test  of  its  purity  is  its  fusing-point,  which 
should  not  be  much  below  +33°. 

Linseed-oil — Flaxseed-oil — Oleum  lini  (U.  S.,  Br.) — is  prepared  on  a 
large  scale  as  an  industrial  product,  and  is  largely  used  by  painters.  Its 
drying  qualities  are  increased  by  charging  it  with  lead  oxide,  by  boiling 
with  litharge  (boiled  oil).  The  raw  oil  has  a  disagreeable  odor  and  a 
nauseous  taste,  is  dark  yellowish  brown  in  color,  and  readily  soluble  in 
ether  and  hot  alcohol.  In  this  oil  oleic  acid  is,  at  least  partially,  replaced 
by  another  fluid  acid,  linoleic  acid,  which,  when  exposed  to  the  air,  gradu- 
ally absorbs  oxygen  and  becomes  thick  and  finally  solid. 

Castor-oil — Oleum  ricini  (U.S.,  Br.) — is  usually  obtained  by  expres- 
sion of  the  seeds,  although  in  some  countries  it  is  prepared  by  decoction 
or  by  extraction  with  alcohol.  It  is  a  thick,  viscid,  yellowish  oil,  has  a  faint 
odor  and  a  nauseous  taste.  It  is  more  soluble  in  alcohol  than  any  other 
fixed  vegetable  oil,  and  is  also  very  soluble  in  ether.  It  saponifies  very 
readily.  Ammonia  separates  from  it  a  crystalline  solid,  fusible  at  66° — 
ricinolamide.  Hot  nitric  acid  attacks  it  energetically,  and  finally  converts 
it  into  suberic  acid. 


Animal  Oils. 

The  principal  oils  of  animal  origin  used  in  the  arts  and  in  medicine  are 
the  following: 

Whale-oil — Train-oil — obtained  by  trying  out  the  fat  or  blubber  of  the 
"right  whale"  and  of  other  species  of  balcence.  It  is  of  sp.  gr.  0.924;  at 
15°;  brownish  in  color;  becomes  solid  at  about  0°;  has  a  very  nauseous  taste 
and  odor;  it  may  be  deodorized  to  a  certain  extent  by  passing  through  it 
a  current  of  steam  heated  to  160°.  It  is  colored  yellow  by  sulphuric 


282  GENERAL   MEDICAL    CHEMISTRY. 

acid;  with  Pontet's  reagent  it  forms  a  yellow  salve,  which  slowly  turns 
brown;  chlorine  blackens  it  immediately. 

Sperm-oil  is  obtained,  along  with  spermaceti,  from  the  cranial  cavities 
of  the  cachalot  or  sperm-whale.  It  is  a  clear,  transparent,  orange-yellow 
oil;  sp.  gr.  0.884  at  15°;  at  —  8°  it  deposits  crystals  of  a  solid  fat.  It 
saponifies  with  difficulty,  and  is  solidified  by  Pontet's  reagent. 

Porpoise-oil ;  a  pale  yellow,  neutral  oil;  sp.  gr.  0.937  at  16°;  solidifies 
at  -15°. 

Dolphin-oil;  a  pale  yellow,  neutral  oil;  sp.  gr.  0.918  at  20°;  when 
cooled  it  deposits  crystals  at  -|-50  and  again  at  — 3°. 

Seal- oil ;  a  dark  brown,  viscid  oil,  having  a  disgusting  odor;  sp.  gr. 
0.9317  at  11°. 

Shark-oil ;  a  pale  yellow,  stinking  oil  of  sp.  gr.  0.870  at  15°. 

These  oils  are  used  in  the  manufacture  of  soft  soaps,  for  illumination, 
and  in  dressing  leather. 

Neatfs-foot  oil — Oleum  bubulum  (U.S.) — is  obtained  by  the  action  of 
boiling  water  upon  the  feet  of  neat  cattle,  horses,  and  sheep,  deprived  of 
the  flesh  and  hoofs.  It  is  straw  yellow  or  reddish  yellow,  odorless,  not 
disagreeable  in  taste,  not  prone  to  rancidity,  does  not  solidify  at  quite 
low  temperatures;  sp.  gr.  at  15°,  0.916.  It  is  bleached,  not  colored,  by 
chlorine;  in  which  it  differs  from  fish-  and  whale-oils.  It  is  used  as  a  lubri- 
cant and  in  pharmacy. 

Lard-oil^  obtained  in  large  quantities  in  the  United  States  as  a  by- 
product in  the  manufacture  of  candles,  etc.,  from  pigs'  fat.  A  light 
yellow  oil,  used  principally  as  a  lubricant;  it  is  not  colored  by  sulphuric 
acid,  but  is  colored  brown  by  a  mixture  of  sulphuric  and  nitric  acids. 

Tallow-oil — obtained  by  expression  with  a  gentle  heat  from  the  fat  of 
the  ox  and  sheep.  Sp.  gr.  0.9003;  light  yellow  in  color.  Colored  brown 
by  sulphuric  acid.  Formerly  this  oil,  under  the  trade-name  of  "oleic 
acid,"  was  simply  a  by-product  in  the  manufacture  of  stearine  candles; 
of  late  years,  however,  it  is  specially  prepared  for  the  manufacture  of 
oleo-margarine. 

Cod-liver  oil — Oleum  morrhuce  (U.  S.,  Br.) — is  obtained  principally  in 
Norway  and  Newfoundland,  from  the  livers  of  codfish,  either  by  ex- 
traction with  water  heated  to  about  80°,  or  by  hanging  the  livers  in  the 
sun  and  collecting  the  oil  which  drips  from  them.  There  are  three  com- 
mercial varieties  of  this  oil:  a.  Brown. — Dark  brown,  with  greenish  reflec- 
tions; sp.  gr.  0.928  at  15°;  has  a  disagreeable,  irritating  taste;  faintly  acid; 
does  not  solidify  at  — 13°.  b.  Pale  brown. — Of  the  color  of  Malaga  wine; 
sp.  gr.  0.934;  has  a  peculiar  odor  and  a  fishy,  irritating  taste;  strongly 
acid.  c.  Pale. — G-olden  yellow;  sp.  gr.  0.928  at  15°;  deposits  a  white  fat 
at  — 13°;  has  a  fresh  odor,  slightly  fishy,  and  a  not  unpleasant  taste,  with- 
out after-taste. 

Pure  cod-liver  oil,  with  a  drop  of  sulphuric  acid,  gives  a  bluish  violet 
aureole,  which  gradually  changes  to  crimson,  and  later  to  brown.  A  drop 
of  fuming  nitric  acid  dropped  into  the  oil  is  surrounded  by  a  pink  aureole 
if  the  oil  be  pure;  if  largely  adulterated  with  other  fish-oils,  the  pink 
color  is  not  observed  and  the  oil  becomes  slightly  cloudy.  Fresh  cod- 
liver  oil  is  not  colored  by  rosaniline.  If  a  third  of  the  oil  is  distilled,  the 
distillate  becomes  solid;  while  if  it  be  contaminated  with  vegetable  oils, 
the  distillate  becomes  liquid. 

Cod-liver  oil  contains,  besides  the  glycerides  of  oleic,  palmitic  and 
stearic  acids,  those  of  butyric  and  acetic  acids,  certain  biliary  principles 
(to  whose  presence  the  sulphuric  acid  reaction  given  above  is  probably 


SOLID    ANIMAL    FATS.  283 

due),  a  phosphorized  fat  of  undetermined  composition,  small  quantities 
of  bromine  and  iodine,  probably  in  the  form  of  organic  compounds,  a  pe- 
culiar fatty  acid  called  gadinic  acid,  which  solidifies  at  00°,  and  a  brown 
substance  called  gaduin  or  gadinine. 

To  which,  if  to  any  of  these  substances,  cod-liver  oil  owes  its  value  as 
a  therapeutic  agent,  is  still  unknown,  although  many  theories  have  been 
advanced.  Certain  it  is,  however,  that  one  of  the  chief  values  of  this  oil 
is  as  a  food  in  a  readily  assimilable  form. 


SOLID  ANIMAL  FATS. 

Condition  in  the  body. — The  glycerides  of  stearic,  palmitic  and  oleic 
acids  exist,  in  health,  in  all,  or  nearly  all,  parts  of  the  body;  in  the  fluids 
in  solution  or  in  suspension,  in  the  form  of  minute  oil-globules;  incorpo- 
rated in  the  solid  or  semi-solid  tissues,  or  deposited  in  collections  in  cer- 
tain locations,  as  under  the  skin,  inclosed  in  cells  of  connective  tissue,  in 
which  the  mixture  of  the  three  glycerides  is  in  such  proportion  that  the 
contents  of  the  cells  are  fluid  at  the  temperature  of  the  body. 

The  total  amount  of  fat  in  the  body  of  a  healthy  adult  is  from  2.5  to 
5  per  cent,  of  the  body-weight,  although  it  may  vary  considerably  from 
that  proportion  in  conditions  not,  strictly  speaking,  pathological.  The 
approximate  quantities  of  fat  in  100  parts  of  the  various  tissues  and  fluids, 
in  health,  are  the  following: 


Urine ?     jBlood 0.4|Cortex  of  brain 5.5 

Perspiration 0.001  (Cartilage 1  .SlBrain 8.0 

Vitreous  humor 0.002 

Saliva 0.02 

Lymph 0.05 

Synovial  fluid 0.06 

Amniotic  fluid 0.2 

Chyle 0.3 

Mucus 0.4 


Bone 1 .4|Hen's  egg 11.6 

Bile 1 .4|White  matter  of  brain.  .20.0 

Crystalline  lens 2. 0|  Nerve-tissue 22. 1 

Liver 2. 4  (Spinal  cord 23.6 


Muscle 3.i 

Hair 4.2 

Milk...  ....  4.3 


Fat-tissue.... 82.7 

Marrow 96.0 


The  amount  of  fat  in  the  body,  under  normal  conditions,  is  usually 
greater  in  women  and  children  than  in  men;  generally  greater  in  middle 
than  in  old  age,  although  in  some  individuals  the  reverse  is  the  case; 
greater  in  the  inhabitants  of  cold  climates  than  in  those  of  hot  countries. 

In  wasting  from  disease  and  from  starvation  the  fats  are  rapidly  ab- 
sorbed, and  are  again  as  rapidly  deposited  when  the  normal  condition  of 
affairs  is  restored. 

Besides  as  a  result  of  the  tendency  to  corpulence,  which  in  some  in- 
dividuals amounts  to  a  pathological  condition,  fats  may  accumulate  in 
certain  tissues  as  a  result  of  morbid  changes.  This  accumulation  may  be 
due  either  to  degeneration  or  to  infiltration.  In  the  former  case,  as  when 
muscular  tissue  degenerates  in  consequence  of  long  disuse,  the  natural 
tissue  disappears  and  is  replaced  by  fat;  in  the  latter  case,  as  in  fatty  in- 
filtration of  the  heart,  oil-globules  are  deposited  between  the  natural 
morphological  elements,  whose  change,  however,  may  subsequently  take 
place  by  true  fatty  degeneration  due  to  pressure.  Fatty  degeneration 
of  the  liver  and  of  other  organs  occurs  also  in  phthisis,  chronic  heart  and 
lung  affections,  as  a  result  of  overfeeding,  from  the  abuse  of  alcoholic 
stimulants,  and  from  the  action  of  certain  poisons,  especially  of  phos- 
phorus. Tumors  composed  of  adipose  tissue  occur  and  are  known  as 
•"  lipomata." 


284  GENERAL    MEDICAL    CHEMISTRY. 

The  greater  part  of  the  fat  of  the  body  enters  it  as  such  with  the  food; 
not  unimportant  quantities  are,  however,  formed  in  the  body,  and  that 
from  the  albuminoid  as  well  as  from  the  starchy  and  saccharine  constitu- 
ents of  the  food.  By  what  steps  this  transformation  takes  place  is  still 
uncertain,  although  there  is  abundant  evidence  that  it  does  occur. 

Those  fats  taken  in  with  the  food  are  unaltered  by  the  digestive  fluids, 
except  in  that  they  are  freed  from  their  enclosing  membranes  in  the 
stomach,  until  they  reach  the. duodenum;  here,  under  the  influence  of  the 
pancreatic  juice,  the  major  part  is  converted  into  a  fine  emulsion,  in  which 
form  it  is  absorbed  by  the  lacteals.  A  smaller  portion  is  saponified,  and 
the  products  of  the  saponification,  free  fatty  acids,  soaps,  and  glycerin, 
subsequently  absorbed  by  lacteals  and  blood-vessels. 

The  service  of  the  fats  in  the  economy  is  undoubtedly  as  a  producer  of 
heat  and  force  by  its  oxidation;  and  by  its  low  power  of  conducting  heat, 
and  the  position  in  which  it  is  deposited  under  the  skin,  as  a  retainer  of 
heat  produced  in  the  body.  The  fats  are  not  discharged  from  the  system 
in  health,  except  the  excess  contained  in  the  food  over  that  which  the 
absorbents  are  capable  of  taking  up,  which  passes  out  with  the  fasces,  a 
small  quantity  distributed  over  the  surface  in  the  perspiration  and  seba- 
ceous secretion  (which  can  hardly  be  said  to  be  eliminated)  and  a  mere 
trace  in  the  urine. 

Animal  Fats  used  in  the  Arts  and  in  Pharmacy. — The  prin- 
cipal of  these  are  lard,  tallow,  and  butter. 

Lard — Adeps  (U.  S.) — is  the  fat  of  the  hog  freed  from  connective  tis- 
sue. It  is  white,  almost  odorless,  almost  tasteless,  soft;  fusible  at  38°; 
readily  saponifiable  by  alkalies;  not  prone  to  rancidity  if  properly  prepared. 

Tallow,  the  purified  fat  of  the  ox  or  sheep;  is  rather  harder  than  lard; 
white,  tasteless,  and  odorless  when  pure;  fuses  at  about  44°;  and  solid- 
ifies at  about  37°. 

Butter,  the  fat  of  milk,  separated  and  made  to  agglomerate  by  agita- 
tion, and  more  or  less  salted  to  insure  its  keeping.  It  consists  of  the 
glycerides  of  stearic,  palmitic,  oleic,  butyric,  capric,  caprylic,  and  caproic 
acids,  with  a  small  amount  of  coloring  matter,  more  or  less  water  and  salt 
and  casein.  Good,  natural  butter  contains  eighty  to  ninety  per  cent,  of 
fat,  six  to  ten  per  cent,  of  water,  two  to  five  per  cent,  of  curd,  and  two  to 
five  per  cent,  of  salt;  fuses  at  from  32.8°  to  34.9°. 

Butter  is  very  liable  to  adulterations,  the  chief  adulterants  being  ex- 
cess of  water  and  salt,  starch,  animal  fats  other  than  those  of  butter, 
artificial  coloring  matters. 

Excess  of  salt  and  water  are  usually  worked  in  together,  the  former 
up  to  fourteen  per  cent,  and  the  latter  to  fifteen  per  cent.  To  determine 
the  presence  of  an  excess  of  water,  about  four  grams  of  the  butter,  taken 
from  the  middle  of  the  lump,  are  weighed  in  a  porcelain  capsule,  in  which 
it  is  heated  over  the  water-bath,  as  long  as  it  loses  weight;  it  is  then 
weighed  again;  the  loss  of  weight  is  that  of  the  quantity  of  water  in  the 
original  weight  of  butter,  less  that  of  the  capsule.  The  proportion  of  .salt 
is  determined  by  incinerating  a  weighed  quantity  of  butter  and  determin- 
mining  the  chlorine  in  the  ash  by  the  nitrate  of  silver  method  (see  Sodium 
Chloride).  Roughly,  the  weight  of  the  ash  may  be  taken  as  salt.  Starch 
is  detected  by  spreading  out  a  thin  layer  of  the  butter,  adding  solution  of 
iodine,  and  examining  under  the  microscope  for  purple  spots. 

To  determine  the  presence  of  foreign  fats,  the  best  method  is  that  of 
Angell  and  Hehner.  A  pear-shaped  bulb  is  made  by  blowing  a  small 
globe  in  the  end  of  a  piece  of  glass  tubing  of  one-fourth  inch  diameter 


SOAPS.  285 

and  drawing  off  a  tapering  neck  very  near  the  bulb,  the  diameter  of  which 
should  be  about  one-half  inch;  enough  mercury  is  then  placed  in  the  bulb 
to  make  the  whole  weigh  3.4  grams,  and  the  open  end  closed  by  fusion. 
To  use  this  little  apparatus,  twenty  to  thirty  grams  of  the  butter  to  be 
tested  are  melted  in  a  beaker  on  the  water-bath,  and,  when  quite  fluid, 
poured  into  a  test-tube  three-fourths  inch  in  internal  diameter  and  six 
inches  long,  until  the  tube  is  filled  to  within  two  inches  of  the  top;  the 
tube  is  then  kept  warm  and  upright  until  the  fat  has  separated  in  a  clear 
layer  above  the  water,  etc.,  after  which  it  is  solidified  by  immersion  in 
water  at  15°;  the  surface  should  only  be  slightly  depressed.  The  test- 
tube  with  the  solidified  butter  is  suspended  in  a  large  beaker  of  cold 
water;  the  small  bulb  is  laid  upon  the  surface  of  the  fat,  which  should  be 
one  and  one-half  inch  below  the  surface  of  the  water  in  the  beaker,  and 
a  thermometer  is  suspended  near  the  test-tube.  The  water  is  now  heated 
until  the  globular  part  of  the  bulb  has  just  sunk  below  the  surface  of  the 
fat,  at  which  point  the  standing  of  the  thermometer  is  read  off;  this  is  the 
"  sinking-point "  of  the  butter,  and  should  be  from  34.3°  to  36.3°.  Oleo- 
margarine, or  butterine,  has  a  lower  sinking-point,  and  butter  adulterated 
with  fats  a  higher  one. 


Soaps. 

These  compounds,  which  have  been  known  from  time  immemorial,  are 
the  metallic  salts  of  stearic,  palmitic,  and  oleic  acids;  those  of  potassium, 
sodium,  and  ammonium  are  soluble  in  water,  while  those  of  other  metals 
are  insoluble;  those  of  potassium  and  sodium  are  also  soluble  in  alcohol 
and  in  ether.  The  sodium  soaps  are  hard,  and  those  of  potassium  soft. 

Soap  is  made  from  almost  any  oil  or  fat,  the  best  from  olive-oil,  or  pea- 
nut- or  palm-oil,  and  lard.  The  first  step  in  the  process  of  manufacture  is 
the  saponification  of  the  fat,  which  consists  in  the  decomposition  of  the 
glyceric  ethers  into  glycerin  and  the  fatty  acids,  and  the  combination  of 
the  latter  with  an  alkaline  metal;  it  is  usually  effected  by  gradually  add- 
ing the  fluid  fat  to  a  weak  boiling  solution  of  caustic  soda  or  potassa  to 
saturation.  From  this  weak  solution  the  soap  is  separated  by  "  salting," 
which  consists  in  adding,  during  constant  agitation,  a  solution  of  caustic 
alkali,  heavily  charged  with  common  salt,  until  the  soap  separates  in 
grumous  masses,  which  float  upon  the  surface  and  are  separated.  Finally 
the  soap  is  pressed  to  separate  adhering  water,  fused,  and  cast  into 
moulds. 

The  varieties  of  soaps  used  in  the  arts  and  in  medicine  are  numerous. 

Yellow  soap  is  made  from  tallow  or  other  animal  fat,  and  about  one- 
third  weight  of  rosin  subsequently  added. 

White  castile  soap — Olive-oil  soap  (Sapo,  U.  S.;  Sapo  durus,  Br.),  is 
pale  grayish  white  in  color,  hard,  dry,  not  greasy;  strongly  alkaline;  very 
soluble  in  alcohol  and  water;  contains  twenty-one  per  cent,  of  water. 
A  marbled  variety  of  the  same  soap  is  made  by  using  a  soda  containing 
ferruginous  matter  and  agitating  the  saponified  fat  at  the  proper  time;  it  is 
harder  than  the  white  variety,  and  contains  less  water — fourteen  per  cent. 
A  soft  or  potash  soap  is  also  made  from  olive-oil,  and,  like  other  soft 
soaps,  contains  an  excess  of  alkali  and  glycerin;  it  is  the  Sapo  mottis 
(U.  S.).  Olive-oil  soaps  are  usually  imported  from  France  and  Spain. 

Almond-oil  soap  is  the  officinal  soap  of  the  French  Codex,  and  con- 
tains glycerin  and  an  excess  of  alkali. 


286  GENERAL    MEDICAL    CHEMISTRY. 

Emplastrum  plumbi  (U.  S.,  Br.)  is  simply  a  lead-soap,  prepared  by 
saponifying  olive-oil,  or  a  mixture  of  olive-oil  and  lard  with  litharge. 

Linimentum  calcis  (U.  S.,  Br.)  is  a  mixture  of  calcium  soap  with  olive- 
or  flaxseed-oil  in  excess. 

All  the  soaps  are  decomposed  by  even  weak  acids,  with  liberation  of 
the  fatty  acids;  by  compounds  of  the  alkaline  earths,  with  formation  of 
an  insoluble  soap;  and  in  the  same  way  by  most  of  the  metallic  salts. 

''"" 


Phosphorized  Fats. 


Lecithins.  —  That  brain-tissue  contains  phosphorus  was  known  as 
early  as  1779,  and  that  this  phosphorus  exists  in  combination  in  a  fat-like 
material  was  determined  in  the  early  part  of  the  present  century.  In 
1851  Gobley  described  a  fatty  material  which  he  obtained  from  the  yolks 
of  eggs,  and  which  he  called  lecithin;  later,  in  1865,  Liebreich  described 
a  substance  also  containing  phosphorus,  which  he  obtained  from  brain- 
tissue,  and  which  he  designated  as  protogon. 

Most  later  authors  have  considered  protogon  as  being  a  mixture  of 
lecithin  and  another  substance  called  cerebrin,  although  Gamgee  ad- 
vances strong  grounds  for  its  admission  as  a  distinct  substance.  The 
study  of  the  constituents  of  brain-  and  nerve-tissue  is  one  surrounded  with 
great  difficulties,  and  has  led  as  yet  to  but  few  results  sufficiently  well  es- 
tablished for  adoption  in  a  work  of  this  nature. 

That  lecithin,  however,  or  rather  a  number  of  lecithins,  exist  in  brain- 
tissue,  in  the  yolks  of  hens'  eggs,  in  fish-roes,  etc.,  may  be  considered  as 
definitely  settled. 

These  substances  are  of  very  complex  constitution;  they  yield,  on  de- 
composition, neurine  (see  p.  206),  stearic,  palmitic,  or  oleic  acid,  and  a 
peculiar  acid,  called  from  its  composition,  glycerophosphoric  acid.  They 
are,  therefor,  glycerophosphoric  acid  in  which  the  remaining  hydrogens  of 
the  glycerin  are  replaced  by  radicals  of  fatty  acids,  and  the  remaining 
oxhydryls  of  the  phosphoric  acid  by  neurine: 

CH,-OH  CHa-0(C18HS50)" 

CH-OH  CH-0  (C18H85O)' 

rn 
\OH  H'~ 

Glycerophosphoric  acid.  Stcarine  lecithin. 

The  lecithins  are  yellowish  white,  waxy,  hygroscopic  solids,  imper- 
fectly crystalline,  soluble  in  ether  and  alcohol,  insoluble  in  water,  in 
which  they  swell  like  starch;  when  ignited  they  burn,  leaving  a  residue 
of  metaphosphoric  acid  and  carbon.  They  form  compounds  with  certain 
salts,  as  platinic  chloride,  and  with  acids.  They  are  readily  decomposed, 
yielding  the  products  mentioned  above. 


ILLUMINATING-GAS.  287 

THIRD  SERIES  OF   HYDROCARBONS. 

SERIES  CnH2n_,. 

The  terms  of  this  series  at  present  known  are: 

Acetylene C2Ha    Crotonylene C4H6 1  Rutylene CioHn 

Allylene C3H4    Valerylene C6H8 1  Benylene Ci5H28 

Acetylene. 

Ethene,  C2H3 — was  discovered  by  Davy.  It  exists  as  a  constituent 
of  coal-gas  ;  it  is  formed  as  a  product  of  the  decomposition,  by  heat  and 
otherwise,  of  a  number  of  organic  substances,  notably  of  hydrocarbons, 
ether,  chloroform,  etc.  It  is  best  prepared  by  passing  a  slow  current  of 
coal-gas  through  a  narrow  tube  through  which  induction  sparks  are  pass- 
ing, directing  the  gas  through  a  solution  of  cuprous  chloride,  and  collect- 
ing and  decomposing  the  precipitate  with  hydrochloric  acid. 

A  most  interesting  method  of  its  formation  is  that  by  direct  synthesis, 
discovered  by  Berthelot:  a  slow  current  of  hydrogen  is  passed  through  a 
glass  globe  in  which  are  the  carbon-points  of  an  electric  light;  the  escap- 
ing gas  contains  acetylene  formed  by  the  direct  union  of  carbon  and 
hydrogen. 

Acetylene  is  a  colorless  gas,  rather  soluble  in  water;  it  has  a  peculiar, 
disagreeable  odor,  which  is  observed  when  a  Bunsen  burner  burns  within 
the  tube,  and  when  a  piece  of  platinum  foil  is  incandescent  in  vapor  of 
ether;  it  burns  with  a  white,  luminous  flame. 

When  mixed  with  oxygen  it  explodes  violently  on  the  approach  of  a 
flame,  a  deposit  of  carbon  being  formed  if  the  amount  of  oxygen  be  defi- 
cient. It  unites  with  nitrogen  under  the  influence  of  the  electric  dis- 
charge, to  form  hydrocyanic  acid.  It  combines  with  hydrogen  to  form 
ethylene.  Mixed  with  chlorine  it  detonates  violently  even  in  diffuse  day- 
light, and  without  the  application  of  heat.  It  may  be  made  to  unite 
with  itself  to  form  its  superior  polymeres: 

G3Ha  C6H6  C8H8  C10H10 

Acetylene.  Benzene.  Styrolene.  Naphthydrene. 

Its  most  characteristic  property  is  that  of  forming  a  blood-red  precipi- 
tate of  cuproso-acetyl  oxide  when  it  is  passed  through  an  ammoniacal 
solution  of  cuprous  chloride,  a  reaction  by  which  the  presence  of  traces 
of  this  gas  may  be  detected;  similar  compounds  are  formed  with  other 
metals.  These  precipitates,  when  dried,  explode  violently  when  sub- 
jected to  shock,  and  it  is  probable  that  explosions  which  sometimes  occur 
without  any  apparent  cause,  in  pipes  through  which  illuminating-gas  is 
conducted,  especially  if  of  brass  or  copper,  are  due  to  their  formation. 


Hluminating--Gas. 

Illuminating-gas  is  now  manufactured  by  a  variety  of  processes, 
almost  every  gas  company  using  some  peculiar  modification  of  the 
method,  or  of  the  nature  and  proportion  of  the  raw  materials;  thus,  we 
have  gas  made  from  wood,  from  coal,  from  fats,  from  petroleum,  and  by 


288 


GENERAL    MEDICAL    CHEMISTRY. 


the  decomposition  of  water  and  subsequent  charging  of  the  gas  with 
the  vapor  of  naphtha.  The  typical  process  is  that  in  which  the  gas  is 
produced  by  heating  cannel  or  other  bituminous  coal  to  bright  redness 
in  retorts.  As  it  issues  from  the  retorts,  the  gas  is  charged  with  sub- 
stances volatile  only  at  high  temperatures;  these  are  deposited  in  the 
condensers  or  coolers,  and  form  coal-  or  gas-tar.  From  the  condensers 
the  gas  passes  through  what  are  known  as  "scrubbers"  and  "lime-puri- 
iiers,"  in  which  it  is  depriv'ed  of  amtrioniacal  compounds  and  other  im- 
purities. As  it  comes  from  the  condensers,  coal-gas  contains: 


*  Acet.ylene. 

*  Ethyl ene. 

*  Marsh-gas. 

*  Butylene. 

*  Propylene. 

*  Benzene. 


*Styro1e-e. 
*  Naphthalene. 
*  Acenaphthalene. 
*  Fluorene. 
*  Propyl  hydride. 
*  Butyl  hydride. 

\  Hydrogen, 
f  Carbon  monoxide, 
f  Carbon  dioxide. 
f  Ammonia. 
j  Cyanogen, 
f  Sulphocyanogen. 

f  Hydrogen  sulphide. 
f  Carbon  disulphide. 
f  Sulphuretted      hy- 
drocarbons, 
f  Nitrogen, 
f  Aqueous  vapor. 


In  passing  through  the  purifiers  the  gas  is  freed  of  the  impurities  to 
a  greater  or  less  extent,  and,  as  usually  delivered  to  consumers,  contains: 


*  Marsh -gas. 

*  Acetylene. 


*  Ethyl  ene.  I  f  Nitrogen 

|  Hydrogen.  |  f  Aqueous  vapor. 

*  Vapors  of  hydrocarbons. 


I  f  Carbon  monoxide. 
I  f  Carbon  dioxide. 


Allylene,  C3H4 — is  a  colorless  gas,  very  soluble  in  alcohol,  quite 
soluble  in  water;  has  a  slightly  less  disagreeable  odor  than  acetylene; 
burns  with  a  smoky  flame.  It  is  obtained  by  a  general  reaction  used  for 
the  obtaining  of  hydrocarbons  of  this  series,  which  consists  in  heating  the 
monobromine  compounds  of  the  corresponding  hydrocarbon  of  the  ethy- 
lene  series  with  sodium  ethyl  oxide: 


C2H3Br 

Monobrom- 
ethylene. 


4-     C,H5NaO     = 


Sodium 
ethyl  oxide. 


NaBr     -f     C9H5HO    + 


Sodium 
bromide. 


Alcohol. 


C.H, 

Acetylene. 


C,H5Br 

Monobrom- 
propylene. 


C3H5NaO 

Sodium 
ethyl  oxide. 


=      NaBr 

Sodium 
bromide. 


C3H5HO 

Alcohol. 


C,H. 

Allylene. 


It  is  distinguished  from  acetylene  by  forming  a  gray  precipitate  with 
mercurous  salts,  a  white  one  with  the  silver  salts,  and  a  yellow  one  with 
the  cuprous  salts. 

Crotonylene,  C4H6 — obtained  by  the  general  method  from  monobrom- 
butylene.  It  is  liquid  below  15°;  boils  at  about  18°;  has  a  powerful  and 
somewhat  alliaceous  odor;  burns  with  a  bright,  smoky  flame.  It  has  also 
been  obtained  by  distilling  erythrite  (q.  v.)  with  formic  acid. 


*  Illuminating  constituents. 


f  Impurities. 


J  Diluent. 


ACIDS    DERIVABLE    FROM    ERTTHRITE.  289 


TETRATOMIC  ALCOHOLS. 

Very  few  of  these  compounds  have  yet  been  obtained.  They  may  be 
regarded  as  the  hydrates  of  the  hydrocarbons  Cn  H2M_2;  as  the  glycols  are 
the  hydrates  of  the  ethylene  series. 

Propylphycite,  C8H4  (OH)4 — is  probably  the  first  term  of  the  series, 
although  its  existence  is  not  yet  well  established. 

CHaOH 

CHOH 

Erythrite — phycite — I  =C4H.(OH)4 —  a  well-defined  com- 

CHOH 


OH 


pound,  was  discovered  in  1848,  as  a  product  of  decomposition  of  ery- 
thrine,  C20H22O10,  which  exists  in  lichens  of  the  genus  rocella.  To  obtain 
it  the  lichens  are  macerated  in  water;  treated  with  powdered  lime;  the 
solution  filtered  after  half  an  hour;  the  filtrate  treated  with  hydrochloric 
acid;  the  gelatinous  precipitate  of  erythrine  is  washed,  dried,  and  intro- 
duced into  a  Papin's  digester  with  a  small  quantity  of  slacked  lime,  and 
heated  to  100°  for  two  hours;  the  liquid  is  filtered  and  slowly  evaporated; 
orcine  separates  first  and  is  removed,  afterward  erythrite,  which  is  puri- 
fied by  recrystallization  from  boiling  alcohol. 

Erythrite  crystallizes  in  large,  brilliant  prisms;  very  soluble  in  water 
and  in  hot  alcohol,  almost  insoluble  in  ether;  it  is  sweetish  in  taste;  its  solu- 
tions neither  affect  polarized  light,  nor  reduce  Fehling's  solution,  nor  are 
capable  of  fermentation;  it  fuses  at  120°,  and  at  300°  is  partly  decom- 
posed, giving  off  an  odor  of  caramel.  Its  watery  solution,  like  that  of 
sugar,  is  capable  of  dissolving  a  considerable  quantity  of  lime,  and  from 
this  solution  alcohol  precipitates  a  definite  compound  of  erythrite  and 
ealcium.  By  oxidation  with  platinum  black  it  yields  erythroglucic  acidy 
C4H8OB.  With  fuming  nitric  acid  it  forms  a  tetranitro  compound,  which 
explodes  under  the  hammer. 


ACIDS  DERIVABLE  FROM  ERYTHRITE. 

Theoretically  erythrite  should,  by  simple  oxidation,  yield  two  acids; 
one  of  the  series  CttH,n05,  and  another  of  the  series  CnH2W._206.  Although 
both  of  these  acids  are  known,  only  the  first,  erythroglucic  acid,  has  been 
obtained  by  oxidation  of  erythrite: 

CH.OH  COOH  COOH 


HOH 


CHOH          CHOH         C 
CHOH          CHOH         CHOH 
CH,OH         CH2OH         COOH 

Errthrite.  Erythroglucic  acid.  Tartaric  acid. 

19 


290  GENERAL    MEDICAL    CHEMISTRY. 


Tartaric  Acids. 

Acidum  tartaricum  (U.  S.,  Br.),  04H606. — There  exist  four  acids 
having  the  composition  04H606  ;  which  differ  from  each  other  only  in 
their  physical  properties,  and  are  very  readily  converted  one  into  another; 
they  are  designated  as:  1st,  Right;  2d,  Left;  3d,  Inactive  tartaric  acid; 
4th,  Racemic  acid.  Right  -or  Dextrotartaric  acid  crystallizes  in  large, 
oblique,  rhombic  prisms,  having  hemihedral  facettes.  Solutions  of  the 
acid  and  its  salts  are  dextrogyrous. 

Left  or  Lcevotartaric  acid  crystallizes  in  the  same  form  as  dextro- 
tartaric  acid,  only  the  hemihedral  facettes  are  on  the  opposite  sides,  so 
that  crystals  of  the  two  acids,  when  held  facing  each  other,  appear  like  the 
reflections  one  of  the  other.  Its  solution  and  those  of  its  salts  are  Isevo- 
gyrous  to  the  same  degree  that  corresponding  solutions  of  dextrotartario 
acid  are  dextrogyrous. 

Racemic  acid  is  a  compound  of  the  two  preceding;  it  forms  crystals 
having  no  hemihedral  facettes,  and  its  solutions  are  without  action  on 
polarized  light.  It  is  readily  separated  into  its  components. 

Inactive  tartaric  acid,  although  resembling  racemic  acid  in  its  crystal- 
line form  and  inactivity  with  respect  to  polarized  light,  differs  essentially 
from  that  acid  in  that  it  cannot  be  decomposed  into  right  and  left  acids, 
and  in  the  method  of  its  production. 

The  tartaric  acid  which  exists  in  nature  is  the  dextrotartaric ;  it 
occurs,  both  free  and  in  combination,  in  the  sap  of  the  vine  and  in  a  great 
number  of  other  vegetable  juices  and  fruits;  it  has  not  been  detected  as  a 
constituent  of  animal  bodies.  Although  this  is  probably  the  only  tartaric 
acid  existing  in  nature,  all  four  varieties  may  and  do  occur  in  the  com- 
mercial acid,  being  formed  during  the  process  of  manufacture. 

Tartaric  acid  is  obtained  in  the  arts  from  hydropotassic  tartrate,  or 
cream  of  tartar  (q.  v.).  This  salt  is  dissolved  in  water  and  the  solution 
boiled  with  chalk  until  its  reaction  is  neutral;  calcic  and  potassic  tartrates 
are  formed: 

2(C4H4Oe,HK)    -f  C03Ca  =  C4H406Ca  +   04H406K9  +  H,0  +  00, 

Hydro-potassic  Calcium  Calcium  Potassio  Water.          Carbon 

tartrate.  carbonate.  tartrate.  tartrate.  dioxide. 

The  insoluble  calcic  salt  is  separated  and  the  potassic  salt  decomposed 
by  treating  the  solution  with  calcic  chloride: 

C4H4OfiKa  +  CaCl3  =  C4H4OfiCa  4-  2KC1 

Potaseio  Calcium  Calcium  Potassium 

tartrate.  chloride,  tartrate.  chloride. 

The  united  deposits  of  calcium  tartrate  are  suspended  in  water,  decom- 
posed with  the  proper  quantity  of  sulphuric  acid,  the  solution  separated 
from  the  deposit  of  calcium  sulphate,  and  evaporated  to  crystallization. 

The  commercial  acid  is  liable  to  contamination  with  sulphuric  acid, 
lead  and  calcium  compounds,  from  which  it  may  be  freed  by  recrystalliza- 
tion.  When  sufficiently  pure  for  pharmaceutic  purposes,  its  solution  is 
not  affected  by  hydrogen  sulphide,  and  gives  no  preciptate  with  calcium 
sulphate  or  ammonium  oxalate,  and  with  barium  chloride  no  precipitate 
not  entirely  soluble  in  nitric  acid.  It  should  not  attract  moisture  from 


CITRIC    ACID.  291 

the  air,  should  be  entirely  soluble  in  alcohol,  and  should  be  entirely 
consumed  when  heated  to  redness  as  platinum  foil. 

The  ordinary  tartaric  acid  crystallizes  in  large  prisms;  very  soluble  in 
•water  and  in  alcohol,  insoluble  in  ether;  permanent  in  air;  acid  in  taste 
and  reaction.  Its  solutions  become  mouldy  on  standing. 

It  fuses  at  170°;  at  180°  it  loses  water  and  is  gradually  converted  into 
an  anhydride;  at  200° — 210°  the  acid  is  decomposed  with  formation  of 
new  volatile  products, ,pyrumc  and  pyrotartaric  acids;  at  higher  tempera- 
tures the  decomposition  is  more  complete,  and  results  in  the  production 
of  acetic  acid,  carbon  dioxide  and  monoxide,  water,  hydrocarbons  and 
charcoal;  if  still  further  heated  in  air,  it  burns  with  an  odor  of  caramel. 
If  kept  in  fusion  for  some  time,  two  molecules  of  the  acid  unite,  with 
loss  of  the  constituents  of  a  molecule  of  water,  to  form  tartralic  or  ditar- 
tric  acid,  C8H,0On. 

Tartaric  acid  is  attacked  by  oxidizing  agents  with  formation  of  carbon 
dioxide,  water,  and,  in  some  instances,  formic  and  oxalic  acids.  Certain 
reducing  agents  convert  it  into  malic  and  succinic  acids.  With  fuming 
nitric  acid  it  forms  a  dinitro-compound,  which  is  very  unstable,  and  which, 
when  decomposed  below  36°,  yields  tartaric  acid.  It  forms  a  precipitate 
with  lime-water,  soluble  in  an  excess  of  water;  in  not  too  dilute  solution 
it  forms  a  precipitate  with  potassium  sulphate  solution;  it  does  not  pre- 
cipitate with  the  salts  of  calcium.  When  heated  with  a  solution  of  auric 
chloride  it  precipitates  the  gold  in  the  metallic  form. 

As  its  formula  indicates  (see  above),  tartaric  acid  is  tetratomic  and 
dibasic;  it  forms  many  salts  which  are  of  medical  importance,  and  ex- 
hibits a  great  tendency  to  the  formation  of  double  salts,  such  as  tartar 
emetic  (q.  v.). 

When  taken  into  the  economy,  as  it  constantly  is -in  the  form  of  tar- 
trates,  the  greater  part  is  oxidized  to  carbonic  acid  (carbonates);  but,  if 
taken  in  sufficient  quantity,  a  portion  is  excreted  unchanged  in  the  urine 
and  perspiration.  The  free  acid  is  poisonous  in  large  doses. 

In  pharmacy  tartaric  acid  is  used  chiefly  in  effervescent  mixtures, 
seidlitz  powder,  etc.,  and  is  frequently  used  in  place  of  the  more  costly 
citric  acid.  In  the  arts  it  is  extensively  consumed  in  processes  of  dyeing. 

There  exist  anhydrides,  ethers,  and  amides  corresponding  to  the  tar- 
taric acids,  none  of  which  is  of  medical  interest. 


Citric  Acid,  C6H8O7+Aq, 

is  best  considered  in  this  place,  although  its  constitution  is  different  from 
that  of  tartaric  acid.  It  exists  in  the  acid  juices  of  many  fruits — lemon, 
strawberry,  gooseberry,  cherry,  orange,  etc. 

It  is  obtained  from  lemon-juice,  which  is  filtered,  boiled,  and  saturated 
with  chalk.  The  insoluble  calcium  citrate  is  separated  and  decomposed 
with  sulphuric  acid,  the  solution  filtered,  and  evaporated  to  crystallization. 

It  crystallizes  in  large,  right  rhombic  prisms,  which  lose  their  aq.  at 
100°;  very  soluble  in  water,  less  soluble  in  alcohol,  sparingly  soluble  in 
ether;  heated  to  100°  it  fuses;  at  175°  it  is  decomposed,  with  loss  of  water 
and  formation  of  aconitic  acid,  C6H6O6;  at  a  higher  temperature,  car- 
bon dioxide  is  given  off,  and  itaconic  acid,  C6H8O4,  and  citraconic  acid, 
C6H6O4,  are  formed. 

Concentrated  sulphuric  acid  decomposes  it  with  evolution  of  carbon 


292  GENERAL    MEDICAL    CHEMISTRY. 

monoxide;  oxidizing  agents  convert  it  into  formic  acid  and  carbon  dioxide; 
or  into  carbon  dioxide  and  acetone;  or  into  oxalic  and  acetic  acids  and 
carbon  dioxide.  It  is  tetratomic  and  tribasic. 


PENTATOMIC  ALCOHOLS. 

Only  two  of  these  compounds  are  known,  and  require  mere  mention. 

Quercite,  C6H13O5 — a  sugar-like  substance  obtained  from  acorns.  It 
forms  hard  crystals,  soluble  in  water  and  in  hot  aqueous  alcohol ;  perma- 
nent in  air;  fuses  at  a  temperature  above  235°,  and  sublimes  with  a  slight 
darkening  in  color.  It  is  not  affected  by  the  alkalies;  does  not  reduce 
Fehling's  solution,  and  is  not  fermentable  ;  with  a  mixture  of  nitric  and 
sulphuric  acids  it  yields  a  detonating  nitro-compound. 

Finite  is  an  isomere  of  quercite,  obtained  from  the  exudations  of  Cali- 
fornia pine  (Pinus  Lambertiana).  It  crystallizes  in  hard,  white,  mam- 
ellated  masses;  very  soluble  in  water,  almost  insoluble  in  alcohol  and 
ether;  its  solution  is  dextrogyrous,  [a]D=+58.6°;  it  fuses  without  de- 
composition at  150°.  It  reduces  solutions  of  silver  nitrate,  but  not  Feh- 
ling's solution;  nor  is  it  capable  of  fermentation. 


FOURTH  SERIES  OF  HYDROCARBONS. 

SERIES  CJl^^. 

But  one  of  the  lower  terms  of  this  series  is  known;  this  is  valylene, 
C5H6,  obtained  by  the  action  of  an  alcoholic  solution  of  potash  on  valery- 
lene  dibromide.  It  is  a  liquid,  boiling  at  45°. 

Among  the  higher  terms  of  the  series  are  many  substances  of  industrial 
and  medical  importance. 

Terebenthene,  C10H16,  is  the  type  of  a  great  number  of  isomeric 
substances  existing  in  the  volatile  oils  or  essences.  It  is  the  chief  con- 
stituent of  oil  of  turpentine. 

To  obtain  it  in  a  state  of  purity,  oil  of  turpentine  is  mixed  with  an 
alkaline  carbonate,  and  distilled  in  vacuo  over  a  water-bath,  or  by  frac- 
tional distillation  of  the  crude  oil,  those  portions  being  collected  which 
pass  over  at  about  156°. 

Pure  terebenthene  is  a  colorless,  mobile  liquid;  has  the  peculiar  odor 
of  turpentine;  boils  at  about  156°;  burns  with  a  smoky,  luminous  flame; 
obtained  from  the  turpentine  of  pinus  maritime*,  it  is  laevogyrous,  puri- 
fied by  distillation  in  vacuo,  [cz]D— — 42.36°,  by  fractional  distillation, 
1a]D— — 40.32°;  that  obtained  from  pinus  australis  is  dextrogyrous, 
a]D=-f  18.9°;  specific  gravity  at  0°=rO.S767. 

It  absorbs  oxygen  rapidly  from  the  air,  whether  pure  or  in  the  com- 
mercial essence,  becoming  thick  and  finally  gummy.  Oxidizing  agents, 
such  as  nitric  acid,  attack  it  energetically,  causing  it  to  ignite  and  burn 
suddenly,  with  separation  of  a  large  volume  of  carbon.  Hydrochloric  acid 
unites  with  it  to  form  a  number  of  compounds,  as  do  also  hydriodic  and 
hydrobromic  acids — all  the  compounds  having  the  odor  of  camphor. 
When  mixed  with  nitric  acid  diluted  with  alcohol  and  exposed  to  the  air, 
it  forms  a  crystalline  pseudo-glycol,  tcrpine.  Chlorine,  bromine,  and  iodine 
form  compounds  of  substitution  or  of  addition. 


FOURTH   SERIES    OF   HYDROCARBONS.  293 

Turpentine — Terebenthina  (U.  S.) — is  the  name  given  to  the  concrete 
juice  of  various  species  of  trees  of  the  genera  Pinus,  Abies,  and  Larix, 
which  consists  of  terebenthene,  its  isomeres,  and  resinous  and  other  sub- 
stances. The  product  differs  in  composition  and  properties  according 
to  the  kind  of  tree  from  which  it  is  produced;  the  varieties  recognized 
by  the  United  States  Dispensatory  are  the  following: 

First. —  White  turpentine —  Common  American  turpentine — obtained 
in  North  Carolina  and  adjacent  States,  from  Pinus  palustris  and  P.  tceda. 
It  is  yellowish  white,  semi-fluid  at  summer  temperature,  hard  and  solid 
when  cooled;  on  exposure  to  air  it  becomes  dry,  hard,  and  brittle.  It  is 
usually  subjected  to  distillation  near  the  place  of  its  collection,  by  which 
process  it  is  separated  into  the  volatile  oil,  or  essence  of  turpentine  (q.  v.)y 
and  resin,  or  colophony  (q.  v.). 

/Second. — European  turpentine — Bordeaux  turpentine — obtained  in 
the  south  of  France,  etc.,  from  P.  sylvestris  and  P.  maritima,  is  the  va- 
riety principally  used  in  Europe,  but  rarely  finds  its  way  to  this  country. 

TJiird. —  Canada  turpentine —  Canada  balsam — Balsam  of  fir — is  pro- 
duced in  Canada  and  Maine  from  abies  balsamea.  It  is  a  tenacious  semi- 
solid,  of  the  consistency  of  honey  when  fresh,  colorless  or  yellowish,  sticky, 
bitter  in  taste,  and  having  a  balsamic  odor;  when  long  exposed  to  the  air, 
or  when  heated  over  the  water-bath,  its  volatile  constituents  are  lost,  and 
it  is  converted  into  a  hard,  brittle  mass. 

Fourth. —  Venice  turpentine — produced  principally  in  Switzerland  from 
larix  Furopcea.  It  is  a  thick,  viscid  liquid,  yellowish  or  greenish  in 
color;  soluble  in  alcohol;  does  not  concrete  as  readily  as  other  turpentines. 

Fifth. —  Chian  turpentine  is  the  product  oipistachia  terebinthus,  grow- 
ing in  the  island  of  Chio,  in  the  JSgean.  It  is  a  thick,  greenish  yellow 
liquid. 

Essence  of  turpentine —  Oil  of  turpentine — Spirits  of  turpentine —  Oleum 
terebinthince  (U.  S.,  Br.)— is  the  volatile  product  of  the  distillation  of  tur- 
pentine. It  is  not  identical  with  terebenthene,  although  that  substance 
is  its  main  constituent;  it  contains  also  hydrocarbons  isomeric  with  tur- 
pentine and  substances  containing  oxygen,  which  either  pre-exist  in  the 
turpentine,  or,  more  usually,  result  from  the  method  of  preparing  the  oil. 
When  recently  distilled,  it  is  a  colorless,  limpid,  neutral  liquid;  sp.  gr. 
0.86;  usually  laevogyrous,  sometimes  dextrogyrous;  when  exposed  to  the 
air  it  rapidly  becomes  yellow  and  viscid.  The  action  of  reagents  upon  it 
is  practically  the  same  as  upon  terebenthene. 

The  number  of  isomerides  existing  in  oil  of  turpentine  is  very  great; 
some  are  optically  active,  others  inactive;  they  also  vary  in  their  specific 
gravities,  fusing-  or  boiling-points,  and  capacity  for  absorbing  oxygen; 
prominent  among  them  are: 


Isoterebenthene  

Specific  grav- 
ity at  60°. 

0.8116 

Fnsing- 
point. 

Boiling- 
point. 

177° 

Terebene  

0  8266 

156° 

Terebenthene  

.    .     0.8271 

156.5* 

Camphenes  . 

.  0.8738 

45° 

160° 

Action  on  the  economy. — Oil  of  turpentine  is  used  medicinally  as  a  stim- 
ulant and  diuretic;  in  large  doses  it  acts  as  a  narcotic-irritant  poison.  .It 
is  eliminated  in  the  form  of  sulphoconjugated  (?)  acids  with  the  urine,  to 
which  it  communicates  an  odor  of  violets. 


294  GENERAL    MEDICAL    CHEMISTRY. 

Isorneres  of  Terebenthene. 

ESSENCES. 

There  exist  a  great  number  of  bodies,  the  products  of  distillation  of 
vegetable  substances,  which  are  known  as  essences,  essential  oils,  volatile 
oils,  distilled  oils,  or  Olea  dfotillata  (Uj  S.).  They  resemble  each  other 
in  being  odorous,  oily,  sparingly  soluble  in  water,  more  or  less  soluble  in 
alcohol  and  ether;  colorless  or  yellowish,  inflammable,  and  prone  to  be- 
come resinous  on  exposure  to  air.  They  are  not  simple  chemical  com- 
pounds, but  mixtures  in  which  some  constituent  predominates,  and  in  many 
of  them  the  principal  ingredient  is  a  hydrocarbon,  isomeric  with  tereben- 
thene,  and  consequently  having  the  composition  nC10H16;  the  number  of 
such  isomeres  is  very  great.  Some  contain  hydrocarbons,  others  alde- 
hydes, acetones,  phenols,  and  ethers. 

Of  the  numerous  other  hydrocarbons  closely  related  to  terebenthene, 
but  two  require  further  consideration  as  being  the  principal  constituents 
of  caoutchouc  and  gutta-percha,  both  of  which  are  isomeric  with  tere- 
benthene. 

Caoutchouc — India-rubber — is  a  peculiar  substance  existing  in  sus- 
pension in  the  milky  juice  of  quite  a  number  of  trees  growing  in  warm 
climates.  It  is,  when  pure,  a  mixture  of  two  hydrocarbons — caoutchene, 
C10H]6,  and  isoprene,  CfiH8. 

The  commercial  article  is  yellowish  brown;  sp.  gr.  0.919  to  0.942;  soft, 
flexible;  almost  impermeable,  but  still  capable  of  acting  as  a  dialyzing 
membrane  when  used  in  sufficiently  thin  layers.  It  is  insoluble  in  water 
and  alcohol,  both  of  which,  however,  it  absorbs  by  long  immersion,  the 
former  to  the  extent  of  twenty -five  per  cent,  and  the  latter  of  twenty  per 
cent,  of  its  own  weight;  it  is  soluble  in  ether,  carbon  disulphide,  petro- 
leum, fatty  and  essential  oils;  its  best  solvent  is  carbon  disulphide,  either 
alone,  or,  better,  mixed  with  five  parts  of  absolute  alcohol. 

It  is  not  acted  upon  by  dilute  mineral  acids,  but  is  attacked  by  con- 
centrated nitric  and  sulphuric  acids,  and  especially  by  a  mixture  of  the 
two.  Alkalies  tend  to  render  it  tougher,  although  a  solution  of  soda  of 
40°  B.  renders  it  soft  after  an  immersion  of  a  few  hours.  Chlorine  at- 
tacks it  after  a  time,  depriving  it  of  its  elasticity,  and  rendering  it  hard 
and  brittle.  When  heated  it  becomes  viscous  at  145°,  and  fuses  at  170° — 
180°  to  a  thick  liquid,  which,  on  cooling,  remains  sticky  and  only  regains 
its  primitive  character  after  a  very  long  time;  on  contact  with  flame  it 
ignites,  burning  with  a  reddish  and  very  smoky  flame,  which  is  ex- 
tinguished with  difficulty. 

The  most  valuable  property  of  india-rubber,  apart  from  its  elasticity, 
is  that  which  it  possesses  of  entering  into  combination  with  sulphur  to 
form  what  is  known  as  vulcanized  rubber,  which  is  produced  (the  details 
of  the  process  vary)  by  heating  together  the  normal  caoutchouc  and  sul- 
phur to  130° — 150°.  Ordinary  vulcanized  rubber  differs  materially  from 
the  natural  gum  in  its  properties;  its  elasticity  and  flexibility  are  much 
increased;  it  does  not  harden  when  exposed  to  cold;  it  only  fuses  at 
200°;  finally,  it  resists  the  action  of  reagents,  of  solvents,  and  of  the  at- 
mosphere much  better  than  does  the  natural  gum. 

Frequently  rubber  tubing  is  too  heavily  charged  with  sulphur  for  cer- 
tain chemical  uses,  in  which  case  it  may  be  desulphurized  by  boiling  with 
dilute  caustic  soda  solution. 


CAMPHORS.  295 

Hard  rubber,  vulcanite,  or  ebonite,  is  a  hard,  tough  variety  of  vulcan- 
ized rubber,  susceptible  of  a  good  polish,  and  a  non-conductor  of  elec- 
tricity; used  in  the  manufacture  of  a  great  many  objects.  It  contains 
twenty  to  thirty-five  per  cent,  of  sulphur  (the  ordinary  vulcanized  rubber 
contains  seven  to  ten  per  cent.),  and  is  prepared  by  a  process  which  re- 
quires great  care  and  experience. 

I  Gutta-percha  is  the  concrete  juice  of  isonandra  gutta.  It  is  a  tough, 
inelastic,  brownish  substance,  having  an  odor  similar  to  that  of  caout- 
chouc; at  ordinary  temperatures  it  is  rather  hard,  but  when  heated  to 
below  the  boiling-point  of  water  it  becomes  soft  and  may  be  moulded, 
or  even  cast,  so  as  to  assume  any  form,  which  it  retains  on  cooling;  it 
may  be  welded  with  great  facility  at  slightly  elevated  temperatures,  is  a 
good  insulating  and  waterproofing  material,  and  is  sufficiently  tough  and 
pliable  for  use  for  belting  for  machinery.  It  is  insoluble  in  water,  alka- 
line solutions,  dilute  acids,  including  hydrofluoric,  and  in  fatty  oils;  it  is 
soluble  in  benzene,  oil  of  turpentine,  essential  oils,  chloroform,  and  es- 
pecially in  carbon  disulphide.  A  solution  in  chloroform  is  officinal  as 
JJiq.  gutta  percJwe  (U.  S.),  and  is  used  to  obtain,  by  its  evaporation,  a 
thin  film  of  gutta  percha  over  parts  which  it  is  desired  to  protect  from 
the  air.  It  is  attacked  by  nitric  and  sulphuric  acids. 

When  exposed  to  air  and  light,  it  is  gradually  changed  from  the  sur- 
face inward,  assuming  a  sharp  acid  odor,  becoming  hard  and  cracked, 
and  even  a  conductor  of  electricity,  thus  losing,  after  a  time,  those  char- 
acters which  render  it  valuable  in  the  arts. 

Gutta-percha  is  a  more  complex  substance  than  caoutchouc,  and  seems 
to  be  made  up  of  three  substances:  Gutta,  Oao  H32,  seventy-five  to  eighty- 
two  per  cent.,  a  white,  tough  substance,  fusing  at  150°,  soluble  in  the 
ordinary  solvents  of  gutta-percha,  but  insoluble  in  alcohol  and  ether. 
Albane,  fourteen  to  nineteen  per  cent.,  a  white,  crystalline  resin,  heavier 
than  water,  fusible  at  160°;  soluble  in  benzine,  essence  of  turpentine, 
carbon  disulphide,  ether,  chloroform,  and  hot  absolute  alcohol;  not  at- 
tacked by  hydrochloric  acid;  its  composition  is  C20H3202.  Fluviale,  four 
to  six  per  cent.,  C20Ha20,  a  yellowish  resin,  slightly  heavier  than  water, 
hard  and  brittle  at  0°,  soft  at  50°,  liquid  at  100°;  soluble  in  the  solvents 
of  gutta-percha. 

Camphors  and  Resins. 

Most  of  the  essential  oils  yield  on  distillation  two  products  of  differ- 
ent boiling-points;  one  of  these  is  a  hydrocarbon,  in  most  instances  of 
the  terebenthene  series,  liquid  at  ordinary  temperatures,  and  sometimes 
known  as  an  eleoptene.  The  other,  of  higher  boiling-point,  and  solid  at 
ordinary  temperatures,  designated  a  stearoptene,  is  an  oxidized  product, 
and  either  exists  as  such  in  the  vegetable  exudation,  or  is  produced 
during  subsequent  treatment. 

Camphors. 

These  stearoptenes  are  probably  aldehydes  or  alcohols  corresponding 
to  hydrocarbons  related  to  terebenthene;  their  composition  is  clearly  de- 
termined, although  their  constitution  is  as  yet  uncertain. 

They  are  quite  numerous,  and  many  of  the  varieties  occur  in  several 
different  modifications;  the  most  important  are: 

Common  Camphor  —  Japan  camphor  —  Laurel  camphor  —  Gam- 


296  GENERAL   MEDICAL   CHEMISTRY. 

pholic  aldehyde—  Camphora  (U.  S.,  Br.) — C10H180. — There  exist  at  least 
three  modifications  of  this  substance,  which  differ  from  each  other,  ap- 
parently, only  in  the  sources  whence  they  are  obtained  and  in  their 
action  upon  polarized  light;  they  are: 

First. — Dextrocamphor,  or  laurel  camphor,  obtained  from  laurus  cam- 
phora  —  Camphore  officinarum — f a] D=  4-47.4°. 

Second. — Lcevocamphor,  obtained  from  matricaria  postlanium — [a] 
D=— 47.4°. 

Third. — Inactive  camphor,  obtainecl  from  the  essential  oils  of  rose- 
mary, sage,  lavender,  and  origanum,  is  without  action  upon  polarized  light. 

The  only  one  of  these  which  is  of  practical  importance  is  the  first, 
which  is  the  ordinary  camphor  of  the  shops. 

It  occurs  as  a  white,  translucent,  crystalline  solid  ;  sp.  gr.  0.986 — 
0.996;  of  a  hot,  bitter  taste,  and  a  well-known  aromatic  odor,  sparingly 
soluble  in  water,  to  which  it  communicates  its  odor.  When  a  small  piece 
is  thrown  upon  water,  it  takes  on  a  rapid,  gyratory  motion  over  the  sur- 
face, which  is  instantly  stopped  when  a  drop  of  essential  oil  is  allowed  to 
fall  on  the  water.  It  is  quite  soluble  in  ether,  acetic  acid,  methyl  alcohol, 
carbon  disulphide,  the  oils,  and  alcohol.  The  spir.  camphorce  is  an  alco- 
holic solution  of  two  ounces  to  the^int.  It  fuses  at  175°  and  boils  at 
204°.  It  is  volatile  at  all  temperatures,  and  is  readily  sublimed. 

It  ignites  readily,  and  burns  with  a  luminous  flame.  Cold  nitric  acid 
dissolves  it,  and  from  the  solution  it  is  precipitated  unchanged  by  water. 
Boiling  nitric  acid  or  potassium  permanganate  solution  oxidize  it  to  dex- 
trocamphoric  acid,  C10H16O4.  Concentrated  sulphuric  acid  forms  with  it  a 
black  solution,  from  which  water  precipitates  an  oily  material  called  cam- 
phrene.  Distilled  with  phosphoric  anhydride,  it  yields  cymene,  C10H14. 
Alkaline  solutions,  by  long  heating  under  pressure,  convert  it  into  cam- 
phic  acid,  C10H16O2,  and  borneol.  Chlorine  attacks  it  with  difficulty. 
Bromine  unites  with  it  to  form  an  unstable  compound,  which  forms  ruby- 
red  crystals  having  the  composition  C10H6COBr2.  These  crystals,  when 
heated  to  80° — 90°,  fuse  and  give  off  hydrobromic  acid,  there  remain- 
ing an  amber-colored  liquid,  which  solidifies  on  cooling  and  yields,  by 
recrystallization  from  boiling  alcohol,  long,  hard,  rectangular  prisms,  in- 
soluble in  water,  soluble  in  alcohol,  ether,  chloroform,  and  oils  ;  this  is 
the  monobromo-camphor,  recently  introduced  as  a  therapeutic  agent. 
When  the  vapor  of  camphor  is  passed  over  a  mixture  of  fused  potash  and 
lime  heated  to  300° — 400°,  it  unites  directly  with  the  potash  to  form  the 
potassium  salt  of  campholic  acid,  C10H18O2. 

Camphor  is  largely  used  in  the  household  as  a  destroyer  of  moths,  and 
iii  medicine  as  an  antispasmodic  ;  in  overdoses  it  acts  as  a  poison,  the 
oases,  however,  usually  terminating  in  recovery.  It  is  said  to  be  a  valu- 
able antidote  in  strychnine-poisoning. 

Borneol — Borneo  camphor — Camphol — Camphyl  alcohol — C10H18O 
— is  usually  obtained  from  dryobalanops  camphora,  although  it  may  be 
obtained  from  other  plants,  and  even  artificially  by  the  hydrogenation  of 
laurel  camphor.  The  product  from  these  different  sources  is  the  same 
chemically,  so  far  as  we  can  determine,  but  varies,  like  the  modifications 
of  camphor,  in  its  action  on  polarized  light ;  thus  the  specific  rotary  power 
is  of 


Borneol  from  amber, 
Borneol  from  dryobalanops, 
Borneol  from  madder, 
Borneol  artificial, 


4.1 


RESINS.  297 

It  forms  small,  white,  transparent,  friable  crystals;  has  an  odor  which 
recalls  at  the  same  time  those  of  laurel  camphor  and  of  pepper;  has  a  hot 
taste  ;  is  insoluble  in  water,  readily  soluble  in  alcohol,  ether,  and  acetic 
acid  ;  fuses  at  198°,  boils  at  212°. 

It  is  a  true  alcohol,  and  enters  into  double  decomposition  vtith  acids  to 
form  ethers.  When  heated  with  phosphoric  anhydride,  it  yields  a  hydro- 
carbon, borneene,  C,eH16.  Oxidized  by  nitric  acid,  it  is  converted  into  laurel 
camphor. 

This  substance  is  very  rarely  exported  from  the  countries  in  which  it 
is  produced. 

Menthol — Menthyl  alcohol — C10H20O — is  a  camphor  existing  in  essen- 
tial oil  of  peppermint.  It  crystallizes  in  colorless  prisms;  fusible  at  36°; 
boiling  at  210°;  sparingly  soluble  in  water;  readily  soluble  in  alcohol, 
ether,  carbon  disulphide,  and  in  acids.  Corresponding  to  it  are  a  series 
of  menthyl  ethers. 

Eucalyptol,  CiaHaoO — is  contained  in  the  leaves  of  eucalyptus  globulin j 
it  is  liquid  at  ordinary  temperatures,  and  boils  at  175°;  by  distillation  with 
phosphoric  anhydride  it  yields  eucalyptene,  C13H1B. 

Terpine — Terebenthene  bihydrate — C10H16,2H2O  +  Aq — is  sometimes 
spontaneously  deposited  from  oil  of  turpentine  containing  water;  it  may 
be  obtained  by  frequently  agitating  for  a  month  or  more  a  mixture  of  oil 
of  turpentine,  alcohol,  and  ordinary  nitric  acid.  It  forms  fine,  large,  rhom- 
bic prisms;  sp.  gr.  1.0994;  sparingly  soluble  in  cold  water;  soluble  in  hot 
water,  alcohol,  and  ether;  fusible  at  103°. 

Terpinol,  (C10H16)2H2O — is  formed  when  terpine  in  solution  in  warm 
water  is  treated  with  a  very  small  quantity  of  sulphuric  or  of  hydrochloric 
acid,  and  distilling.  It  is  a  colorless  liquid;  has  an  odor  of  hyacinth;  sp. 
gr.  0.852;  boils  at  168°,  at  which  temperature  it  suffers  partial  decompo- 
sition. It  appears  to  possess  the  function  of  an  ether. 

Resins. 

Notwithstanding  the  wide  diffusion  and  industrial  importance  of  these 
substances,  and  owing  to  the  uncertainty  still  existing  as  to  their  chem- 
ical nature,  it  is  difficult  to  define  precisely  what  is  meant  by  a  resin. 

They  are  generally  the  products  of  oxidation  of  the  hydrocarbons  allied 
to  terebenthene;  are  amorphous  (rarely  crystalline);  insoluble  in  water; 
soluble  in  alcohol,  ether,  and  essences.  Many  of  them  contain  acids. 

They  may  be  divided  into  several  groups,  according  to  the  nature  of 
their  constituents:  1st,  Balsams,  which  are  usually  soft  or  liquid,  and  are 
distinguished  by  containing  free  cinnamic  or  benzoic  acid  (q.  v.).  The 
principal  members  of  this  group  are  benzoin,  liquidambar,  Peru  balsam, 
styrax,  and  balsam  tolu.  2d.  Oleo-resins  consist  of  a  true  resin  mixed 
with  an  oil,  and  usually  with  an  oxidized  product  other  than  cinnamie 
or  benzoic  acid.  The  principal  members  of  this  group  are  Burgundy  and 
Canada  pitch,  Mecca  balsam,  and  the  resins  of  capsicum,  copaiva,  cubebs, 
elemi,  labdanum,  and  lupulin.  3d.  Gum-resins  are  mixtures  of  true  re- 
sins and  gums.  Many  of  them  are  possessed  of  medicinal  qualities,  aloes, 
ammoniac,  asafcetida,  bdellium,  euphorbium,  galbanum,  gamboge,  guaiac, 
myrrh,  olibanum,  opoponax,  and  scammony.  4th.  True  resins  are  hard 
substances  obtainable  from  the  members  of  the  three  previous  classes,  and 
containing  neither  essences,  gums,  nor  aromatic  acids.  Such  are  colophony 
or  rosin,  copal,  dammar,  dragon's  blood,  jalap,  lac,  mastic,  and  sandarac. 
5th.  Fossil  resins,  such  as  amber,  asphalt,  and  ozocerite. 


298  GENERAL    MEDICAL    CHEMISTRY. 


HEXATOMIC  ALCOHOLS. 

There  exist,  so  far  as  at  present  known,  but  two  alcohols  of  this  series, 
isomeres  of  each  other.  They  may  be  regarded  as  the  hydrates  of  a  hy- 
drocarbon of  the  terebenthene  series,  06H8,  which  is  only  known  in  com- 
bination. They  are  ma?inite.&nd  dulcite. 

Mannite  —  Fraxine — Mannityl  hfydrate — Mannitic  alcohol — C6Hg 
(OH)6 — was  first  obtained  from  manna,  of  which  it  forms  sixty  to  eighty 
per  cent.  It  exists  also  in  a  great  number  of  vegetables,  and  in  cider 
and  wine,  being  formed  as  one  of  the  products  of  viscous  fermentation. 
It  has  also  been  obtained  by  partial  synthesis,  by  the  action  of  nascent 
hydrogen  on  inverted  cane-  and  milk-sugar.  It  is  best  prepared  from 
manna  by  extraction  with  boiling  alcohol,  recrystallization,  and  decolor- 
ization  if  necessary. 

It  crystallizes  in  silky  prisms,  usually  arranged  in  radiating  bundles. 
It  is  sweetish  in  taste;  fermentable  with  difficulty;  without  action  on  polar- 
ized light;  soluble  in  water  and  alcohol;  insoluble  in  ether;  fusible  at 
160°;  it  boils  at  200°. 

When  heated  to  100°  with  hydrochloric  acid  for  some  time,  it  is  con- 
rerted  into  mannitan,  CdHiaO6.  With  the  acids  generally  it  combines, 
with  elimination  of  water,  to  form  mannitic  ethers;  it  also  dissolves  in  al- 
kaline solutions.  It  is  not  capable  of  reducing  the  cupropotassic  solu- 
tions, either  hot  or  cold.  Nitric  acid  oxidizes  it  to  saccharic  acid  (q.  v.), 
and  ultimately  to  oxalic  acid.  By  the  action  of  moist  platinum-black  a 
portion  is  converted  into  mannitic  acid,  C6HiaO,,  and  a  portion  into  man- 
nitose,  C6H13OC. 

Dulcite — Melampyrine — Dulcose — C6H14O6 — the  isomere  of  mannite, 
is  obtained  from  a  Madagascar  plant  of  the  genus  melampyrum.  It  re- 
sembles mannite  closely  in  its  properties  and  reactions,  but  differs  from 
it  in  fusing  at  182°,  and  in  yielding,  when  oxidized  by  nitric  acid,  mucitJ 
in  place  of  saccharic  acid. 

Saccharic  acid,  C4H4  (OH)4  (COOH)2— is  a  dibasic  acid  produced 
by  the  oxidation  of  mannite,  cane-sugar,  and  other  kinds  of  sugar.  It 
forms  a  non-crystalline,  friable  mass;  deliquescent;  soluble  in  water  and 
alcohol;  insoluble  in  ether;  it  is  dextrogyrous  when  made  from  cane- 
sugar.  It  forms  a  series  of  salts  and  ethers  called  saccharates. 

Mucic  acid,  CCH10O8 — is  a  dibasic  acid,  isomeric  with  saccharic 
acid,  which  it  closely  resembles.  It  is  formed  by  the  oxidation  of  dulcite, 
milk-sugar,  or  gum  arabic,  by  nitric  acid. 

It  is  a  white,  crystalline  powder;  very  sparingly  soluble  in  cold  water, 
insoluble  in  alcohol.  By  long  boiling  with  water  it  is  converted  into 
another  isomere,  paramucic  acid,  soluble  in  water  and  alcohol.  Sulphuric 
acid  dissolves  it,  the  solution  being  red  and  containing  a  sulphoconjugate 
acid.  Nitric  acid  by  prolonged  action  oxidizes  it  to  racemic  and  oxalic 
acids.  When  subjected  to  dry  distillation  it  is  decomposed  into  water, 
carbon  dioxide,  and  pyromucic  acid,  C5H4O3. 

Corresponding  to  pyromucic  acid  is  an  aldehyde,  called  fiirfurol,  or 
oil  of  bran,  a  colorless,  highly  aromatic  oil,  sp.  gr.  1.17;  boiling-point, 
162°;  prepared  by  distilling  bran,  starch,  sawdust,  etc.,  with  dilute  sul- 
phuric acid. 


GLUCOSES. 


299 


CARBOHYDRATES. 

The  substances  classed  under  this  head  are  composed  of  carbon,  hy- 
drogen, and  oxygen;  they  all  contain  six  atoms  of  carbon  or  some  multiple 
of  that  number,  and  the  hydrogen  and  oxygen  which  they  contain  are 
t  always  in  the  same  proportion  to  each  other  as  that  in  which  they  exist  in 
water.  Their  precise  constitution  is,  as  yet,  not  definitely  settled, 
although  there  are  very  strong  grounds  for  believing  that  they  are  all  deriv- 
atives of  hexatomic  alcohols,  and  that  they  are,  some  of  them  aldehyds, 
others  alcohols,  and  others  ethers.  Most  of  them  are  important  constitu- 
ents of  animal  or  vegetable  organisms,  and  but  few  of  them  have  been 
hitherto  produced  artificially — none,  so  far  as  we  know,  by  complete 
synthesis. 

They  are  divisible  into  three  well-marked  groups,  the  members  of 
each  of  which  are  isomeric  with  each  other,  and  have  many  important 
characters  in  common.  These  groups  are  the  following: 


I.  GLUCOSES. 


+  Glucose. 

(Dextrose.) 
— Laevulose. 

Mannitose. 
-f-Galactose. 

Inosite. 
—  Sorbin. 
— Eucalin. 


II.  SACCHAROSES. 


•f  Saccharose. 
+  Lactose. 
+  Maltose. 
4-Melitose. 
+  Melezitose. 
H-  Trehalose. 
4-  My  cose. 

Synanthrose. 
-f  Parasaccharose. 


III.  AMYLOSES. 


+  Starch. 
H-Glycogen. 
+ Dextrin. 
— Inulin. 

Tunicin. 

Cellulose. 

Gums. 


Glucoses,  C6H18Oe. 

Glucose —  Grape-sugar — Dextrose — Liver-sugar — Diabetic  sugar. — 
The  substance  from  which  this  group  takes  its  name  is  widely  diffused 
in  nature.  It  exists,  accompanied  by  lasvulose,  or  saccharose,  in  all 
sweet  and  acidulous  fruits;  in  many  vegetable  juices;  in  honey;  in  the 
animal  economy  in  the  contents  of  the  intestines,  in  the  liver,  bile, 
thymus,  heart,  lungs,  blood,  and  in  small  quantity  in  the  urine.  Patho- 
logically it  is  found  in  the  saliva,  perspiration,  faeces,  and  enormously 
increased  in  the  blood  and  urine  in  diabetes  mellitus  (see  below).  It 
may  also  be  obtained  by  decomposition  of  certain  vegetable  substances 
called  glucosides  (q.  v.). 

It  can  be,  and  is,  in  the  arts,  prepared  artificially  by  heating  starch  or 
cellulose  for  twenty-four  to  thirty-six  hours  with  a  dilute  mineral  acid 
(sulphuric).  Glucose  obtained  by  this  method  is  very  largely  used,  both 
legitimately  and  fraudulently;  it  is,  however,  liable  to  contamination  with 
traces  of  arsenic,  which  it  receives  from  the  sulphuric  acid.  Starch  is 
also  converted  into  glucose  by  the  influence  of  a  peculiar  ferment,  dias- 
tase, formed  during  the  germination  of  grain. 

Glucose  crystallizes  with  difficulty  from  its  aqueous  solution  in  white, 
opaque,  spheroidal  masses  containing  1  aq. ;  from  alcohol  in  fine,  trans- 
parent, anhydrous  prisms;  at  about  60  degrees  in  dry  air  the  hydrated 


300  GENERAL    MEDICAL   CHEMISTRY. 

glucose  loses  its  water.  It  is  soluble  in  all  proportions  in  hot  water; 
in  one-third  part  of  cold  water  (less  soluble  than  cane-sugar);  soluble  in 
alcohol.  It  is  less  sweet  in  taste  than  cane-sugar,  two  and  one-half  parts 
of  glucose  being  required  to  produce  the  same  sweetening  as  one  part  of 
saccharose.  Solutions  of  glucose  are  dextrogyrous  \a\  D=  +57.6°.  When 
heated  to  170°  it  loses  water,  and  is  converted  into  glucosan,  C6H100B. 

When  heated  with  the  diluted  mineral  acids,  glucose  is  decomposed, 
yielding  a  brown  substance,  ulmic  acid,  and,  in  the  presence  of  air,  formic 
acid.  It  dissolves  in  concentrated  sulphuric  acid  without  coloration, 
forming  sulphoglucic  acid.  Cold,  concentrated  nitric  acid  converts  it  into 
nitro-glucose  /  hot  dilute  nitric  acid  oxidizes  and  decomposes  it  to  a  mix- 
ture of  oxalic  and  oxysaccharic  acids.  With  the  organic  acids  it  forms  a 
number  of  ethers. 

Solutions  of  glucose  dissolve  potash,  soda,  lime,  baryta,  and  the  oxides 
of  lead  and  copper,  with  which  it  forms  well-defined  compounds,  which 
are,  however,  very  prone  to  decomposition.  When  glucose  solution  is 
heated  with  an  alkali,  it  turns  brown  (yellow  if  the  quantity  of  glucose  be 
small),  and  assumes  a  peculiar,  molasses-like  odor;  this  change  is  due  to 
the  formation  of  melassic  and  glucic  acids  (see  below). 

Glucose  precipitates  silver  from  solutions  of  its  salts,  and  in  the  pres- 
ence of  free  ammonia  the  metal  adheres  to  the  sides  of  the  glass  vessel  as 
a  brilliant  mirror.  When  an  alkaline  solution  of  a  cupric  salt  is  heated 
in  the  presence  of  glucose,  the  sugar  reduces  the  copper  salt  and  precipi- 
tates cuprous  oxide  (see  below).  Mercury  is  precipitated  from  an  alka- 
line solution  of  mercuric  cyanide,  when  heated  with  glucose.  It  forms 
definite,  crystalline  compounds  with  sodium  chloride.  Sodium  amalgam 
converts  glucose  in  aqueous  solution  into  mannite.  Subnitrate  of  bis- 
muth, suspended  in  a  hot  solution  of  glucose,  containing  sodium  car- 
bonate, turns  black  or  brown  from  its  reduction  to  bismuth.  In  the 
presence  of  yeast  it  is  converted  into  alcohol  and  carbon  dioxide,  by 
fermentation  (see  pp.  170,  303);  in  the  presence  of  sour  milk  or  of  cheese, 
it  enters  into  lactic  fermentation. 

If  a  solution  of  glucose  be  rendered  faintly  blue  with  indigo  solution, 
then  faintly  alkaline  with  sodium  carbonate  solution,  and  heated  to  near 
boiling  without  agitation,  the  color  changes  to  violet  and  then  to  yellow. 
The  blue  color  is  restored  by  agitation. 

Physiological. — The  greater  part  of  the  glucose  in  the  economy  in 
health  is  introduced  with  the  food,  either  in  its  own  form  or  as  other  car- 
bohydrates, which  by  digestion  are  converted  into  glucose  ;  a  certain 
quantity  is  also  produced  in  the  liver  at  the  expense  of  glycogen,  a  for- 
mation which  continues  for  some  time  after  death.  In  some  forms  of 
diabetes  the  production  of  glucose  in  the  liver  is  undoubtedly  greatly 
increased.  The  quantity  of  sugar  normally  exsisting  in  the  blood  varies 
from  0.81  to  1.231  part  per  thousand;  in  diabetes  it  rises  as  high  as  5.8 
parts  per  thousand. 

Under  normal  conditions  and  with  food  not  too  rich  in  starch  and 
saccharine  materials,  the  quantity  of  sugar  eliminated  as  such  is  exceed- 
ingly small — so  small  indeed  that  some  observers  have  contested  the  fact 
of  any  being  eliminated  in  health.  It  is  oxidized  in  the  body,  and  the 
ultimate  products  of  such  oxidation  eliminated  as  carbon  dioxide  and 
water.  Whether  or  no  intermediate  products  are  formed,  is  still  uncer- 
tain ;  the  probability,  however,  is  that  there  are.  The  oxidation  of  sugar 
is  impeded  in  diabetes.  Where  this  oxidation,  or  any  of  its  steps,  occurs, 
is  at  present  a  matter  of  conjecture  merely;  if,  as  is  usually  believed, 


GLUCOSES.  301 

glucose  disappears  to  a  marked  extent  in  the  passage  of  the  blood  through 
the  lungs,  the  fact  is  a  strong  support  of  the  view  that  its  transformation 
into  carbon  dioxide  and  water  does  not  occur  as  a  simple  oxidation,  as  the 
notion  that  sugar  or  any  other  substance  is  "  burned  "  in  the  lung,  beyond 
the  small  amount  required  by  the  nutrition  of  the  organ  itself,  is  scarcely 
tenable  at  the  present  day. 

So  long  as  the  quantity  of  glucose  in  the  blood  remains  at  or  below 
the  normal  percentage,  it  is  not  eliminated  in  the  urine  in  quantities 
appreciable  by  the  tests  usually  employed;  when,  however,  the  amount 
of  glucose  in  the  blood  surpasses  this  limit  from  any  cause,  the  urine 
becomes  saccharine,  and  that  to  an  extent  proportional  to  the  increase  of 
glucose  in  the  circulating  fluids.  The  causes  which  may  bring  about  such 
an  increase  are  numerous  and  varied;  many  of  them  are  entirely  consistent 
with  health,  and  the  mere  presence  of  increased  quantities  of  sugar  in  the 
urine  is  no  proof,  taken  by  itself,  of  the  existence  of  diabetes.  Sugar  is 
detectable  by  the  ordinary  tests  in  the  urine  under  the  following  circum- 
stances: Physiologically. — 1st,  in  the  urine  of  pregnant  women  and  dur- 
ing lactation;  it  appears  in  the  latter  stages  of  gestation  and  does  not 
disappear  entirely  until  the  suppression  of  the  lacteal  secretion.  2d,  in 
small  quantities  in  sucking  children  from  eight  days  to  two  and  one-half 
months.  3d,  in  the  urine  of  old  persons  (seventy  to  eighty  years).  4th, 
in  those  whose  food  contains  a  large  amount  of  starchy  or  saccharine 
material;  to  this  cause  is  due  the  apparent  prevalence  of  diabetes  in  certain 
localities,  as  in  districts  where  the  different  varieties  of  sugar  are  pro- 
duced. Pathologically. — 1st,  in  abnormally  stout  persons,  especially  in 
old  persons  and  in  women  at  the  period  of  the  menopause;  the  quantity 
does  not  exceed  eight  to  twelve  grams  per  1,000  c.c.,  and  disappears  when 
starchy  and  saccharine  food  is  withheld;  this  form  of  glycosuria  is  very 
liable  to  develop  into  true  diabetes  when  it  appears  in  yojing  persons. 
2d,  in  diseases  attended  with  an  interference  with  the  respiratory  pro- 
cesses— lung  diseases,  etc.  3d,  in  diseases  in  which  there  is  interference 
with  the  hepatic  circulation — hepatic  congestion,  compression  of  the  portal 
vein  by  biliary  calculi,  cirrhosis,  atrophy,  fatty  degeneration,  etc.  4th,  in 
many  cerebral  and  cerebro-spinal  disturbances — general  paresis,  dementia, 
epilepsy;  by  puncture  of  the  fourth  ventricle.  5th,  in  intermittent  and 
typhus  fevers.  6th,  by  the  action  of  many  poisons — carbon  monoxide, 
arsenic,  chloroform,  curari;  by  injection  into  an  artery  of  ether,  ammo- 
nia, phosphoric  acid,  sodium  chloride,  amyl  nitrite,  glycogen.  7th,  in 
true  diabetes  the  elimination  of  sugar  in  the  urine  is  constant,  unless 
arrested  by  suitable  regulation  of  diet,  and  not  temporary,  as  in  the  con- 
ditions previously  mentioned.  The  quantity  of  urine  is  increased,  some- 
times enormously,  and  it  is  of  high  specific  gravity.  The  elimination  of 
urea  is  increased  absolutely,  although  the  quantity  in  1,000  c.c.  may  be 
less  than  that  normally  existing  in  that  bulk  of  urine.  The  quantity  of 
sugar  in  diabetic  urine  is  sometimes  enormous;  an  elimination  of  200  grams 
in  twenty-four  hours  is  by  no  means  uncommon;  instances  in  which  the 
amount  has  reached  400  to  GOO  grams  are  recorded,  and  one  case  in  which 
no  less  than  1,376  grams  were  discharged  in  one  day.  The  elimination  is 
not  the  same  at  all  hours  of  the  day;  during  the  night  less  sugar  is  voided 
than  during  the  day;  the  hourly  elimination  increases  after  meals,  reach- 
ing its  maximum  in  four  hours,  after  which  it  diminishes  to  reach  the 
minimum  in  six  to  seven  hours,  when  it  may  disappear  entirely  ;  this 
variation  i*  more  pronounced  the  more  copious  the  meal.  It  is  obvious 
from  the  above,  that,  in  order  that  quantitative  determinations  of  sugar  in 


302 


GENERAL    MEDICAL    CHEMISTRY. 


urine  shall  be  of  clinical  value,  it  is  necessary  that  the  determination  be 
made  in  a  sample  taken  from  the  mixed  urine  of  twenty-four  hours. 

The  relation  existing  between  the  quantity  of  sugar  in  the  blood  and 
its  elimination  by  the  urine  in  diabetes  is  well  shown  by  the  following  re- 
sults of  Pavy,  which  also  show  the  beneficial  effects  of  restricting  the  diet: 


V 

QBINB. 

BLOOD. 

Quantity  in 
24  hours. 

Specific 
gravity. 

Sugar  excreted 
in  24  hours. 

Sugar  in 
1.000  parts. 

Sugar  in 
1,000  parts. 

Case  I.  Mixed  diet  

6608  c.c. 

1040 

751  6  grams. 

109  91 

5  763 

Case  II   Mixed  diet         

6474  c  c 

1041 

633  0  grams 

94  08 

5  545 

Case  II.  Restricted  diet  

3407  c  c 

1031 

245  2  grains 

61  34 

2  625 

Case  III.  Mixed  diet       

5878  c  c. 

1036 

567  7  grams. 

93  39 

4  970 

Case  III.  Restricted  diet  

2470  c.c. 

1033 

115.8  grams. 

45  49 

2.789 

Case  IV.  Partly  restricted  diet.. 
Case  IV.  Partly  restricted  diet,  ) 
3£  months  later.  .  .  .  ) 

1704  c.c. 
852  c.c. 

1036 
1034 

21.81  grams. 
14.40  grams. 

48.11 
31.76 

1.848 
1.543 

Tests  for  the  presence  of  glucose. — A  saccharine  urine  is  usually  abun- 
dant in  quantity,  pale  in  color,  of  high  specific  gravity,  covered  with  a 
persistent  froth  on  being  shaken,  and  exhales  a  peculiar  odor;  when  evap- 
orated it  leaves  a  sticky  residue.  The  presence  of  glucose  in  urine  is 
indicated  by  the  following  tests: 

If  the  urine  be  albuminous,  it  is  indispensable  that  the  albumen  be 
separated  before  any  of  the  tests  for  sugar  are  applied;  this  is  done  by 
adding  one  or  two  drops  of  acetic  acid,  or,  if  the  urine  be  alkaline,  just 
enough  acetic  acid  to  turn  the  reaction  to  acid,  and  no  more,  heating 
over  the  water-bath  until  the  albumen  has  separated  in  flocks,  and 
filtering. 

First. — When  examined  by  the  polarimeter  (see  p.  303)  it  deviates 
the  plane  of  polarization  to  the  right. 

Second. — When  mixed  with  an  equal  volume  of  liquor  potassae  and 
heated,  it  turns  yellow,  and,  if  sugar  be  abundant,  brown;  a  molasses-like 
odor  is  at  the  same  time  observable  (Moore's  test). 

TJiird. — The  urine,  rendered  faintly  blue  with  indigo  solution  and 
faintly  alkaline  with  sodium  carbonate,  and  heated  to  boiling  without 
agitation,  turns  violet  and  then  yellow  if  sugar  be  present;  on  agitation 
the  blue  color  is  restored  (Mulder-Neubauer  test). 

Fourth. — About  1  c.c.  of  the  urine,  diluted  with  twice  its  bulk  of  water, 
is  treated  with  two  or  three  drops  of  cupric  sulphate  solution  and  about 
1  c.c.  of  caustic  potassa  solution;  if  sugar  be  present  the  bluish  precipi- 
tate is  dissolved  on  agitation,  forming  a  blue  solution;  the  clear  blue  fluid, 
when  heated  to  near  boiling,  deposits  a  yellow,  orange,  or  red  precipitate 
of  cuprous  oxide  if  sugar  be  present  (Trommer's  test).  In  the  applica- 
tion of  this  test  an  excess  of  cupric  sulphate  is  to  be  avoided,  lest  the 
color  be  masked  by  the  formation  of  the  black  cupric  oxide.  Sometimes 
no  precipitate  is  formed,  but  the  liquid  changes  in  color  from  blue  to 
yellow;  this  occurs  in  the  presence  of  small  quantities  of  cupric  salt  and 
large  quantities  of  sugar,  the  cuprous  oxide  being  held  in  solution  by  the 
excess  of  glucose;  in  this  case  the  test  is  to  be  repeated,  using  a  sample 
of  urine  more  diluted  with  water.  In  some  instances,  also,  the  reaction 
is  interfered  with  by  excess  of  normal  constituents  of  the  urine,  uric  acid, 
creatinine,  coloring  matter,  etc.,  and,  instead  of  a  bright  precipitate,  a 


GLUCOSES.  303 

muddy  deposit  is  formed;  when  this  occurs  the  urine  is  heated  with  ani- 
mal charcoal,  and  filtered;  the  filtrate  evaporated  to  dryness;  the  residue 
extracted  with  alcohol;  the  alcoholic  extract  evaporated;  the  residue 
redissolved  in  water,  and  tested  as  described  above. 

Fifth. — Four  or  five  cubic  centimetres  of  Fehling's  solution  (see  p. 
304)  are  heated  in  a  test-tube  to  boiling;  it  should  remain  unaltered;  the 
urine  is  then  added  guttatim;  if  it  contain  sugar,  the  mixture  turns  green 
and  a  yellow  or  red  precipitate  of  cuprous  oxide  is  formed,  usually  darker 
in  color  than  that  obtained  by  Trommer's  test.  The  absence  of  glucose 
is  not  to  be  inferred  until  a  bulk  of  urine  equal  to  that  of  the  Fehling's 
solution  used  has  been  added,  and,  the  mixture  boiled  from  time  to  time 
without  the  formation  of  a  precipitate.  This  test  is  certainly  the  most 
convenient  and  the  most  reliable  for  clinical  purposes. 

Sixth. — A  few  cubic  centimetres  of  the  urine  are  mixed  in  a  test-tube 
with  an  equal  volume  of  solution  of  sodium  carbonate  (one  part  crystal, 
carbonate  and  three  parts  water),  a  few  granules  of  bismuth  subnitrate 
are  added,  and  the  mixture  boiled  for  some  time  (until  it  begins  to  "  bump," 
if  necessary);  if  sugar  be  present,  the  bismuth  powder  turns  brown  or 
black  by  reduction  to  elementary  bismuth  (Boettger's  test).  No  other 
normal  constituent  of  the  urine  reacts  with  this  test;  a  fallacy  is,  how- 
ever, possible  from  the  presence  of  some  compound,  which,  by  giving  up 
sulphur,  may  cause  the  formation  of  the  black  bismuth  sulphide;  to  guard 
against  this,  when  an  affirmative  result  has  been  obtained,  another  sample 
of  urine  is  rendered  alkaline  with  caustic  potassa  solution  and  boiled  with 
pulverized  litharge;  the  powder  should  not  turn  black. 

Use  may  also  be  made  in  this  test  of  an  alkaline  solution  of  bismuth, 
made  by  dissolving  four  grams  of  Rochelle  salts  in  100  grams  of  caustic 
potassa  solution  of  sp.  gr.  1.33,  warming  gently,  and  adding  bismuth  sub- 
nitrate  as  long  as  it  dissolves  (about  two  grams).  A  few  drops  of  this  so- 
lution are  added  to  three  or  four  cubic  centimetres  of  the  urine,  which  is 
then  boiled.  The  reagent  does  not  keep  well. 

Seventh. — A  solution  of  sugar,  mixed  with  good  yeast  and  kept  at  25°, 
is  decomposed  into  carbon  dioxide  and  water.  To  apply  the  fermentation- 
test  to  urine,  take  three  test-tubes,  A,  B,  and  C,  place  in  each  some  washed 
(or  compressed)  yeast,  fill  A  completely  with  the  urine  to  be  tested,  and 
place  it  in  an  inverted  position,  the  mouth  below  the  surface  of  some  of  the 
same  urine  in  another  vessel  (the  entrance  of  air  being  prevented,  during 
the  inversion,  by  closing  the  opening  of  the  tube  with  the  finger,  or  a 
cork  on  the  end  of  a  wire,  until  it  has  been  brought  below  the  surface  of 
the  urine).  Fill  B  completely  with  some  urine  to  which  glucose  has  been 
added,  and  C  with  distilled  water,  and  invert  them  in  the  same  way  as 
A:  B  in  saccharine  urine,  and  C  in  distilled  water.  Leave  all  three 
tubes  in  a  place  where  the  temperature  is  about  25°,  for  twelve  hours, 
and  then  examine  them.  If  gas  have  collected  in  B  over  the  surface  of 
the  liquid,  and  none  in  A,  the  urine  is  free  from  sugar;  if  gas  has  collected 
in  both  A  and  B,  and  not  in  0,  the  urine  contains  sugar;  if  no  gas  has 
collected  in  B,  the  yeast  is  worthless,  and  if  any  gas  be  found  in  C,  the 
yeast  itself  has  given  off  CO2;  in  the  last  two  cases  the  process  must  be 
repeated  with  a  new  sample  of  yeast. 

Quantitative  determination  of  glucose. — First. — By  the  polar  imeter. — 
The  filtered  urine  is  observed  by  the  polariscope  (see  p.  31)  and  the  mean 
of  half  a  dozen  readings  taken  as  the  angle  of  deviation;  from  this  the 

percentage  of  sugar  is  determined  by  the  formula  p=-—— — -,  in    which 

i)  4  .0  X  I 


304  GENERAL    MEDICAL    CHEMISTRY. 

prrrthe  weight,  in  grams,  of  glucose  in  1  c.c.  of  urine;  a=the  angle  of 
deviation;  /—the  length  of  the  tube  in  decimeters.  The  same  formula 
may  be  used  for  other  substances  by  substituting  for  57.6  the  value  of 
[a]D  for  that  substance. 

If  the  urine  contain  albumen,  it  must  be  removed,  as  it  exerts  an  ac- 
tion on  polarized  light  opposite  to  that  of  glucose.  It  is  always  prefer- 
able, if  possible,  to  observe  the  urine  without  treatment  for  decoloriza- 
tion;  if,  however,  it  be  too  highly  colored,  some  treatment  becomes  neces- 
sary. The  use  of  animal  charcoal  for  this  purpose  should  be  avoided,  as 
it  retains  a  considerable  quantity  of  sugar;  the  best  method  is  to  add  a 
known  volume  of  lead  subacetate  and  filter,  account  being  taken  in  the 
calculation  of  the  dilution  so  caused. 

Second. — By  specific  gravity'  Roberts  method. — The  specific  gravity 
of  the  urine  is  carefully  determined  at  25°;  yeast  is  then  added,  and  the 
mixture  kept  at  25°  until  fermentation  is  complete;  the  specific  gravity  is 
again  observed,  and  will  be  found  to  be  lower  then  before;  each  degree  of 
diminution  represents  0.2196  grams  of  sugar  in  100  c.c.  of  urine. 

Neithery?rs£  nor  second  gives  strictly  accurate  results,  even  when  care- 
fully conducted;  the  results  are,  however,  sufficiently  accurate  for  medical 
purposes. 

Third. — By  Fchling*s  solution. — Of  the  many  formulae  for  Fehling's 
solutions,  the  one  to  which  we  give  the  preference  is  that  of  Dr.  Piffard. 
Two  solutions  are  required: 

I.   Cupric  sulphate  (pure,  crystals) 51.98  grams. 

Water 500.0  c.c. 

II.  Rochelle  salt  (pure,  crystals) 259.9  grams. 

Sodic  hydrate  solution,  sp.  gr.  1.12 1000.0  c.c. 

When  required  for  use,  one  volume  of  No.  I.  is  mixed  with  two  vol- 
umes of  No.  II.  The  copper  contained  in  20  c.c.  of  this  mixture  is  pre- 
cipitated as  cuprous  oxide  by  0.1  gram  glucose. 

To  use  the  solution,  20  c.c.  of  the  mixed  solutions  are  placed  in  a  flask 
of  250 — 300  c.c.  capacity,  40  c.c.  of  distilled  water  are  added,  the  whole 
thoroughly  mixed  and  heated  to  boiling.  On  the  other  hand,  the  urine 
to  be  tested  is  diluted  with  four  times  its  volume,  if  poor  in  sugar,  and 
with  nine  times  its  volume  if  highly  saccharine  (the  degree  of  dilution 
required  is,  with  a  little  practice,  readily  determined  by  the  appearance 
of  the  deposit  obtained  in  the  qualitative  testing);  the  water  and  urine 
are  thoroughly  mixed  and  a  burette  filled  with  the  mixture.  A  few  drops 
of  aqua  ammonias  are  added  to  the  Fehling's  solution  and  the  diluted 
urine  added,  in  small  portions  toward  the  end,  until  the  blue  color  is 
entirely  discharged — the  contents  of  the  flask  being  made  to  boil  briskly 
between  each  addition  from  the  burette.  When  the  liquid  in  the  flask 
shows  no  blue  color  when  looked  through  with  a  white  background, 
the  reading  of  the  burette  is  taken;  this  reading,  divided  by  five  if  the 
urine  was  diluted  with  four  volumes  of  water,  or  by  ten  if  with  nine 
volumes,  gives  the  number  of  cubic  centimetres  of  urine  containing  0.1 
gram  of  glucose;  and  consequently  the  elimination  of  glucose  in 
twenty-four  hours,  in  decigrams,  is  obtained  by  dividing  the  number  of 
cubic  centimetres  of  urine  in  twenty-four  hours  by  the  result  obtained 
above. 


GLUCOSES.  305 

Example. — 20  c.c.  Fehling's  solution  used,  and  urine  diluted  with  four 
volumes  of  water. 

36  5 
Reading  of  burette:  36.5  c.c.    — ~ —  =  7.3  c.c.  urine  contain  0.1  gram 

glucose.     Patient    is   passing    2,436    c.c.    urine    in    twenty-four    hours. 

«  JQ/7 

— '— — =  333.6  decigr.  —  33.36  gram  glucose  in  twenty-four  hours. 
7.o 

The  accuracy  of  the  determination  may  be  controlled  by  filtering  off 
some  of  the  fluid  from  the  flask  at  the  end  of  the  reaction;  a  portion  of 
the  filtrate  is  acidulated  with  acetic  acid  and  treated  with  potassium  fer- 
rocyanide  solution;  if  it  turn  reddish  brown,  the  reduction  has  not  been 
complete,  and  the  result  is  affected  with  a  plus  error.  To  another  portion 
of  the  filtrate  a  few  drops  of  cupric  sulphate  solution  are  added  and  the 
mixture  boiled;  if  any  precipitation  of  cuprous  oxide  be  observed,  an  ex- 
cess of  urine  has  been  added,  and  the  result  obtained  is  less  than  the 
true  one. 

This  method,  when  carefully  conducted  with  accurately  prepared  and 
undeteriorated  solutions,  is  the  best  adapted  to  clinical  uses.  The  copper 
solution  should  be  kept  in  the  dark,  in  a  well-closed  bottle,  arid  the  stopper 
and  neck  of  the  No.  II.  solution  should  be  well  coated  with  paraffin. 

Fourth. —  Gravimetric  method. — When  more  accurate  results  than 
are  obtainable  by  Fehling's  volumetric  process  are  desired,  recourse  must 
be  had  to  a  determination  of  the  weight  of  cuprous  oxide  obtained  by 
reduction.  A  small  quantity  of  freshly  prepared  Fehling's  solution  is 
heated  to  boiling  in  a  small  flask;  to  it  is  gradually  added,  with  the  pre- 
cautions observed  in  the  volumetric  method,  a  known  volume  of  urine, 
such  that  at  the  end  of  the  reduction  there  shall  remain  an  excess  of  un- 
reduced copper  salt.  The  flask  is  now  completely  filled  with  boiling  water, 
corked,  and  allowed  to  cool.  The  alkaline  fluid  is  separated  as  rapidly 
as  possible  from  the  precipitated  oxide  by  decantation  and  filtration 
through  a  small  double  filter,  and  the  precipitate  and  flask  repeatedly 
washed  with  hot  water  until  the  washings  are  no  longer  alkaline;  a  small 
portion  of  the  precipitate  remains  adhering  to  the  walls  of  the  flask.  The 
iilter  and  its  contents  are  dried  and  burned  in  a  weighed  porcelain  cru- 
cible; when  this  has  cooled,  the  flask  is  rinsed  out  with  a  small  quantity 
of  nitric  acid;  this  is  added  to  the  contents  of  the  crucible,  evaporated 
over  the  water-bath,  the  crucible  slowly  heated  to  redness,  cooled,  and 
weighed;  the  difference  between  this  last  weight  and  that  of  the  crucible  4- 
that  of  the  filter-ash,  is  the  weight  of  cupric  oxide,  of  which  220  parts=100 
parts  of  glucose. 

Lsevulose —  TTncrystallizable  sugar — forms  the  uncrystallizable  por- 
tion of  the  sugar  of  fruits  and  of  honey,  in  which  it  is  associated  with 
glucose;  it  is  also  produced  artificially  by  the  prolonged  action  of  boil- 
ing water  upon  inulin,  and  as  one  of  the  constituents  of  inverted  sugar 
(see  p.  308).  It  may  be  separated  from  inverted  sugar  by  adding  calcio 
hydrate,  expressing  the  soluble  calcium-glucose  compound,  suspending 
the  sparingly  soluble  laevulose-calcium  compound  in  water,  decomposing 
with  oxalic  acid,  and  evaporating  the  solution. 

Lsevulose  is  not  capable  of  crystallization,  but  may  be  obtained  as  a 
thick  syrup  ;  very  deliquescent  and  soluble  in  water,  insoluble  in  absolute 
alcohol;  it  is  sweeter  but  less  readily  fermentable  than  glucose,  which  it 
equals  in  the  readiness  with  which  it  reduces  cupro-potassic  solutions. 
Its  prominent  physical  property,  and  that  to  which  it  owes  its  name,  is 
20 


306  GENERAL    MEDICAL    CHEMISTRY. 

its  strong  left-handed  polarization,  [«]D=  — 106°  at  15°.     "When  heated 
to  170°,  it  is  converted  into  the  solid,  amorphous  Icevulosan9  CeH10O5. 

]\Tannitose  is  obtained  by  the  oxidation  of  mannite,  whose  aldehyde 
it  probably  is.  It  is  a  yellow,  uncrystallizable  sugar,  having  many  of  the 
characters  of  glucose,  but  being  optically  inactive. 

Galactose — sometimes  improperly  called  lactose — is  formed  by  the 
action  of  dilute  acids  upon  lactose,  milk-sugar,  as  glucose  is  formed  from 
saccharose.  It  differs  from  glucose  in  crystallizing  more  readily,  in  being 
very  sparingly  soluble  in  cold  alcohol,  in  its  action  upon  polarized  light, 
[«]D  =4-83.33°,  and  in  being  oxidized  to  mucic  acid  by  nitric  acid. 

Inosite — Muscle-sugar — exists  in  the  liquid  of  muscular  tissue,  in  the 
lungs,  kidneys,  liver,  spleen,  brain,  and  blood;  pathologically,  in  the 
urine  in  Bright's,  diabetes,  and  after  the  use  of  drastics  in  uraemia,  and 
in  the  contents  of  hydatid  cysts;  also  in  the  seeds  and  leaves  of  certain 
plants.  What  the  source  and  function  of  inosite  in  the  animal  economy 
may  be  is  still  a  matter  of  conjecture. 

It  may  be  prepared  from  muscular  tissue  or  from  green  beans;  the 
latter  are  reduced  to  a  pulp,  boiled  with  water  for  half  an  hour,  expressed, 
the  liquid  reduced  to  a  syrup  over  the  water-bath,  treated  with  alcohol 
until  a  persistent  deposit  is  formed,  and  set  aside;  crystalline  crusts  of 
inosite  separate. 

It  forms  long,  colorless,  monoclinic  crystals,  containing  two  molecules 
of  water  of  crystallization,  usually  arranged  in  groups  having  a  cauliflower- 
like  appearance.  It  effloresces  in  dry  air;  has  a  distinctly  sweet  taste;  is 
easily  soluble  in  water,  difficultly  in  alcohol;  insoluble  in  absolute  alcohol 
and  in  ether;  it  is  without  action  upon  polarized  light. 

The  position  of  inosite  in  this  series  is  based  entirely  upon  its  chem- 
ical composition,  as  it  does  not  possess  the  other  characteristics  of  the 
group.  It  does  not  enter  directly  into  alcoholic  fermentation,  although 
upon  contact  with  putrefying  animal  matters  it  produces  lactic  and  butyric 
acids;  when  boiled  with  barium  or  potassium  hydrate,  it  is  not  even  col- 
ored; in  the  presence  of  inosite,  potash  precipitates  with  cupric  sulphate 
solution,  the  precipitate  being  redissolved  in  an  excess  of  potash;  but  no 
reduction  takes  place  upon  boiling  the  blue  solution. 

The  presence  of  inosite  is  indicated  by  the  following  reactions :  Scherer's. 
— Treated  with  nitric  acid,  the  solution  evaporated  to  near  dryness,  and 
the  residue  moistened  with  ammonium  hydrate  and  calcium  chloride,  and 
again  evaporated;  a  rose-pink  color  is  produced.  Succeeds  only  with 
nearly  pure  inosite.  Gallois'. — Mercuric  nitrate  produces,  in  solutions  of 
inosite,  a  yellow  precipitate  which,  on  cautious  heating,  turns  red;  the 
color  disappears  on  cooling,  and  reappears  on  heating. 

Sorbin — obtained  from  the  fermented  juice  of  berries  of  the  moun- 
tain ash,  in  which  it  is  formed  by  the  decomposition  of  malic  acid.  It 
forms  colorless  crystals,  sweet,  hard,  and  transparent  ;  very  soluble  in 
water;  very  sparingly  soluble  in  hot  alcohol;  its  solutions  are  Isevogyrous, 
[«]Drr: — 35.97°;  are  not  fermentable,  but  reduce  Fehling's  solution. 

Eucalin — formed  by  the  fermentation  of  melitose;  it  appears  as  a 
faintly  sweet,  syrupy  liquid;  dextrogyrous,  [a]D=-f  50°  about;  it  reduces 
cupro-potassic  solutions,  and  is  oxidized  by  nitric  acid  to  oxalic  acid. 


SACCHAROSES.  307 


Saccharoses,  CjaH22On. 

Saccharose —  Cane-sugar — Beet-sugar — is  by  far  the  most  important 
member  of  the  group;  it  has  been  known  from  early  antiquity,  and  is 
very  abundant  in  vegetable  nature;  it  exists  in  many  roots,  fruits,  and 
grasses,  and  is  produced  principally,  not  to  say  exclusively,  from  the  sugar- 
cane, saccharum  officinarum,  sorghum,  sorghum  saccharatum,  beet,  beta 
vulgaris,  and  sugar-maple,  acer  saccharinum. 

For  the  extraction  of  sugar  from  the  canes,  these  are  crushed,  the  ex- 
pressed juice  is  drawn  off  into  large  pans,  in  which  it  is  heated  to  about 
100°;  milk  of  lime  is  now  added,  which  causes  the  precipitation  of  impu- 
rities, albumen,  wax,  calcic  phosphate,  etc. ;  the  clear  liquid  is  drawn  off, 
and  "delimed"  by  passing  a  current  of  carbon  dioxide  through  it;  the 
clear  liquid  is  again  drawn  off  and  evaporated,  during  agitation,  to  the 
crystallizing-point;  the  product  is  drained,  leaving  what  is  termed  "raw" 
or  "  muscovado "  sugar,  while  the  liquid  which  drains  off  is  molasses, 
Syrupus  fuscus  (U.  S.).  The  sugar  so  obtained  is  unfit  for  human  con- 
sumption, and  is  purified  by  the  process  of  "  refining,"  which  consists  es- 
sentially in  adding  to  the  raw  sugar,  in  solution,  albumen  in  some  form, 
filtering  first  through  canvas,  afterward  through  animal  charcoal;  the 
clear  liquid  is  evaporated  in  "  vacuum-pans  "  at  a  temperature  not-exceed- 
ing 72°,  to  the  crystallizing-point;  the  product  is  allowed  to  crystallize  in 
earthen  moulds,  a  saturated  solution  of  pure  sugar  is  poured  upon  the 
crystalline  mass  in  order  to  displace  the  uncrystallizable  sugar  which  still 
remains,  and  the  loaf  is  finally  dried  in  an  oven.  The  liquid  displaced  as 
above  is  what  is  known  as  "  sugar-house  syrup,"  a  product  which  is  now, 
however,  largely  and  fraudulently  produced  from  artificial  glucose. 

Pure  sugar  should  be  entirely  soluble  in  water;  the  solution  should  not 
turn  brown  when  warmed  with  dilute  potassium  hydrate  solution;  should 
not  reduce  Fehling's  solution;  and  should  give  no  precipitate  with  ammo- 
nium oxalate. 

Beet-sugar  is  the  same  as  cane-sugar,  except  that,  as  usually  met 
with  in  commerce,  it  is  lighter,  bulk  for  bulk.  "  Sugar-candy,"  or  "  rock- 
candy,"  is  cane-sugar  allowed  to  crystallize  slowly  from  a  concentrated 
solution  without  agitation.  Maple-sugar  is  a  partially  refined,  but  not 
decolorized  variety  of  cane-sugar. 

Saccharose  crystallizes,  as  usually  seen,  in  small,  white,  monoclinic 
prisms;  or  as  sugar-candy,  in  large,  yellowish,  transparent  crystals;  sp. 
gr.  1.606.  It  is  very  soluble  in  water,  dissolving  in  about  one-third  its 
weight  of  cold  water,  and  more  abundantly  in  hot  water;  it  is  insoluble 
in  absolute  alcohol  or  ether,  and  its  solubility  in  water  is  progressively 
diminished  by  the  addition  of  alcohol.  Aqueous  solutions  of  cane-sugar 
are  dextrogyrous,  [«]„=-{- 73. 8°. 

When  saccharose  is  heated  to  160°  it  fuses,  and  the  liquid,  on  cooling, 
solidifies  to  a  yellow,  transparent,  amorphous  mass  known  as  "  barley- 
sugar";  at  a  slightly  higher  temperature  it  is  decomposed  into  glucose 
and  Isevulosan;  at  a  still  higher  temperature,  water  is  given  off,  and  the 
glucose  already  formed  is  converted  into  glucosan;  at  210°  the  evolution 
of  water  is  more  abundant,  and  there  remains  a  brown  material  known  as 
"  caramel,"  or  "  burnt  sugar,"  a  tasteless  substance,  insoluble  in  strong 
alcohol,  but  soluble  in  water  or  aqueous  alcohol,  and  used  to  communicate 
color  to  spirits;  finally,  at  higher  temperatures,  methyl  hydride  and  the 


308  GENERAL    MEDICAL    CHEMISTRY. 

two  oxides  of  carbon  are  given  off;  a  brown  oil,  acetone,  acetic  acid,  and 
aldehyde  distil  over,  and  a  carbonaceous  residue  remains. 

If  saccharose  be  boiled  for  some  time  with  water,  it  is  converted  into 
inverted  sugar,  which  is  a  mixture  of  glucose  and  laevulose: 


Saccharose.        Water.        Dextrose.  Lsevulose. 

With  a  solution  of  saccharose  the  polarization  is  dextrogyrous,  but,  after 
inversion,  it  becomes  lasvogyrous,  because  the  left-handed  action  of  the 
molecule  of  laevulose  produced,  [a]D=—  106°,  is  only  partly  neutralized 
by  the  right-handed  action  of  the  glucose,  [a]  D  =4-5  7.  6°.  This  inversion 
of  cane-sugar  is  utilized  in  the  testing  of  samples  of  sugar.  On  the  other 
hand,  it  is  to  avoid  its  occurrence,  and  the  consequent  loss  of  sugar,  that 
the  vacuum-pan  is  used  in  refining  —  its  object  being  to  remove  the  water 
at  a  low  temperature. 

Those  acids  which  are  not  oxidizing  agents  act  upon  saccharose  in 
three  ways,  according  to  circumstances:  1st,  if  tartaric  and  other  organic 
acids  be  heated  for  some  time  with  saccharose  to  100°  —  120°,  compounds 
known  as  saccharides,  and  having  the  constitution  of  ethers,  are  formed; 
2d,  heated  with  mineral  acids,  even  dilute,  and  less  rapidly  with  some  or- 
ganic acids,  saccharose  is  quickly  converted  into  inverted  sugar;  3d,  con- 
centrated acids  decompose  cane-sugar  entirely,  more  rapidly  when  heated 
than  in  the  cold;  with  hydrochloric  acid,  formic  acid  and  a  brown,  flocculent 
material  (ulmic  acid  ?)  are  formed  ;  with  sulphuric  acid,  sulphur  dioxide 
and  water  are  formed,  and  a  voluminous  mass  of  charcoal  remains.  Ox- 
alic acid,  aided  by  heat,  produces  carbon  dioxide,  formic  acid,  and  a  brown 
substance  (humine  ?). 

Oxidizing  agents  act  energetically  upon  cane-sugar,  which  is  a  good 
reducing  agent.  With  potassium  chlorate,  sugar  forms  a  mixture  which 
detonates  when  subjected  to  shock,  arid  which  deflagrates  when  moistened 
•with  sulphuric  acid.  Dilute  nitric  acid,  when  heated  with  saccharose, 
oxidizes  it  to  saccharic  and  oxalic  acids.  Concentrated  nitric  acid,  alone 
or  mixed  with  sulphuric  acid,  converts  it  into  the  explosive  nitro-sctccha- 
rose.  Potassium  permanganate,  in  acid  solution,  oxidizes  it  completely 
to  carbon  dioxide  and  water. 

Cane-sugar  reduces  the  compounds  of  silver,  mercury  and  gold,  when 
heated  with  their  solutions;  it  does  not  reduce  the  cupro-potassic  solutions 
in  the  cold,  but  effects  their  reduction  when  heated  with  them  to  an  ex- 
tent proportional  to  the  amount  of  excess  of  alkali  present. 

When  ground  up  with  potash,  or  moderately  heated  with  liquor  po- 
tassas,  cane-sugar  does  not  turn  brown,  as  does  glucose;  but  by  long  ebul- 
lition it  is  decomposed  by  the  alkalies  much  less  readily  than  glucose, 
with  formation  of  acids  of  the  fatty  series  and  oxalic  acid. 

With  the  bases,  saccharose  is  capable  of  forming  definite  compounds 
called  sucrates  (improperly  saccharates,  a  name  belonging  to  the  salts  of 
saccharic  acid).  With  calcium  it  forms  no  less  than  five  compounds. 
Hydrate  of  calcium  dissolves  readily  in  solutions  of  sugar,  with  formation 
of  a  calcium  compound,  soluble  in  water,  containing  an  excess  of  sugar; 
a  solution  containing  one  hundred  parts  of  sugar  in  six  hundred  parts  of 
water  dissolves  thirty-two  parts  of  calcic  oxide.  These  solutions  have  an 
alkaline  taste;  are  decomposed,  with  formation  of  a  gelatinous  precipi- 
tate, when  heated,  and  with  deposition  of  calcium  carbonate  and  regenera- 
tion of  saccharose,  when  treated  with  carbon  dioxide.  Quantities  of  cal- 


SACCHAROSES.  309 

cium  sucrates  are  frequently  introduced  into  sugars  to  increase  their 
weight — an  adulteration  the  less  readily  detected,  as  the  sucrate  dissolves 
with  the  susrar.  Calcium  sucrates  exist  in  the  Llq.  calcis  saccharatus 
(B.  P.). 

Yeast  causes  fermentation  of  solutions  of  cane-sugar,  but  only  after 
its  conversion  into  glucose;  fermentation  is  also  caused  by  exposing  a 
solution  of  sugar  containing  ammonium  phosphate  to  the  air. 

During  the  process  of  digestion,  probably  in  the  small  intestine,  cane- 
sugar  is  converted  into  glucose. 

Lactose — Milk-sugar — Lactine — Saccharum  lactis  (U.  S.,  Br.) — has 
hitherto  been  found  only  in  the  milk  of  the  mammalia.  It  may  be  ob- 
tained from  skim-milk  by  coagulating  the  casein  with  a  small  quantity  of 
sulphuric  acid,  filtering,  evaporating,  redissolving,  decolorizing  with  animal 
charcoal,  and  recrystallizing. 

It  forms  prismatic  crystals;  sp.  gr.  1.53;  hard,  transparent,  faintly 
sweet,  soluble  in  six  parts  of  cold  water  and  in  two  and  one-half  parts  of 
boiling  water,  soluble  in  acetic  acid,  insoluble  in  alcohol  and  in  ether;  its 
solutions  are  dextrogyrous,  [a]D= +59.3°.  The  crystals,  dried  at  100°, 
contains  1  aq.,  which  they  lose  at  150°. 

Lactose  is  not  altered  by  contact  with  air.  Heated  with  dilute  mineral 
or  with  strong  organic  acids,  it  is  converted  into  galactose.  Nitric  acid 
oxidizes  it  to  mucic  and  oxalic  acids;  a  mixture  of  nitric  and  sulphuric 
acids  converts  it  into  an  explosive  nitro-compound.  With  organic  acids 
it  forms  ethers.  With  soda,  potash  and  lime  it  forms  compounds  similar 
to  those  of  saccharose,  from  which  lactose  may  be  recovered  by  neutraliza- 
tion, unless  they  have  been  heated  to  100°,  at  which  temperature  they  are 
decomposed.  If  cupric  sulphate  solution  be  added  to  a  solution  of  lactose 
and  afterward  potassium  hydrate  solution,  a  precipitate  is  formed  which 
is  redissolved  in  an  excess  of  alkali;  the  cupric  compound  in  this  solu- 
tion is  reduced,  on  boiling,  with  precipitation  of  cuprous  oxide.  Lactose 
also  reduces  Fehling's  solution. 

In  the  presence  of  yeast,  lactose  is  capable  of  alcoholic  fermentation, 
which  takes  place  slowly  and,  as  it  appears,  without  previous  transforma- 
tion of  the  lactose  into  either  glucose  or  galactose.  On  contact  with 
putrefying  albuminoids  it  enters  into  lactic  fermentation. 

The  average  proportion  of  lactose  in  different  milks  is  as  follows:  Cow, 
5.5  per  cent.;  mare,  5.5;  ass,  5.8;  human,  5.3;  sheep,  4.2;  goat,  4.0. 
When  taken  internally,  it  is  converted  into  galactose  by  the  pancreatic 
secretion;  when  injected  into  the  blood,  it  does  not  appear  in  the  urine, 
which,  however,  contains  glucose. 

Maltose — A  sugar  closely  resembling  glucose  in  many  of  its  proper- 
ties, and  existing  in  malt,  being  the  first  product  of  the  action  of  diastase 
upon  starch.  It  crystallizes  as  does  glucose,  but  differs  from  that  sugar 
in  being  less  soluble  in  alcohol  and  in  exerting  a  dextrogyratory  power 
three  times  as  great. 

Melitose  is  obtained  from  the  sweet  exudation  formed  by  various 
species  of  Australian  eucalyptus  (Australian  manna),  from  which  it  may 
be  extracted  by  solution  in  water,  decolorization  by  animal  charcoal,  and 
crystallization. 

It  crystallizes  in  long  needles,  with  3  aq.,  of  which  it  loses  two  at 
100°,  and  the  last  at  130°;  it  is  very  soluble  in  water,  the  solutions  being 
sweet,  and  dextrogyrous,  [«]D—  4-102°. 

Dilute  acids  convert  it  into  glucose  and  eucalin;  it  is  not  colored  when 
boiled  with  alkalies,  nor  does  it  reduce  cupro-potassic  solutions. 


310  GENERAL    MEDICAL    CHEMISTRY. 

Melezitose  is  obtained  from  an  exudation  of  Larix  europcea  (Brian- 
90-n  manna).  It  forms  small,  monoclinic  prisms,  sweet,  efflorescent,  very 
soluble  in  water.  Its  solutions  are  dextrogyrous,  [a]D=:94.10,  do  not  re- 
duce cupro-potassic  solutions,  are  not  fermentable,  and  are  converted,  by 
boiling  with  dilute  acids,  into  solutions  of  glucose. 

Trehalose  is  obtained  from  a  Turkish  manna,  known  as  trehala.  It 
crystallizes  in  hard  octahedra  with  2  aq.,  which  it  loses  at  100°.  It  does 
not  reduce  Fehling's  solution;  is  not  fermentable,  is  very  soluble  in  water; 
the  solution  being  dextrogyrous,  [«]„== +220°. 

Mycose  is  a  sugar  existing  in  ergot.  It  resembles  trehalose  in  all  its 
properties,  except  that  it  does  not  entirely  lose  its  water  of  crystallization 
at  100°,  and  that  it  has  a  lower  dextrogyratory  action, 

Synanthrose  exists,  accompanied  by  inuline  and  glucose  in  the  ripe 
tubercles  of  dahlia,  helianthus,  etc.  It  crystallizes  with  1  aq. ;  is  not 
directly  fermentable;  has  no  action  upon  polarized  light;  is  not  colored 
by  cold  potash  solution;  and  only  reduces  cupro-potassic  solutions  after 
prolonged  boiling. 

Parasaccharose  is  an  isomeric  modification  of  cane-sugar,  produced 
by  the  fermentation  in  summer  of  solutions  of  cane-sugar  by  exposure  to 
air  in  the  presence  of  ammonium  phosphate.  It  differs  from  saccharose 
in  its  rotary  power,  [a]D=-"-107°;  and  in  its  power  to  reduce  alkaline 
solutions  of  cupric  salts. 


Amyloses,  n(C6H1006). 

Starch — Amylum — the  most  important  member  of  the  group,  is  very 
widely  disseminated  in  the  vegetable  kingdom,  existing,  as  it  does,  in  the 
roots,  stems,  and  seeds  of  all  plants. 

It  is  prepared  extensively  for  use  in  the  arts  and  as  an  article  of  diet 
from  rice,  wheat,  potatoes,  maniot,  beans,  sago,  arrow-root,  etc.  The  pro- 
cess generally  followed  consists  in  steeping  the  comminuted  vegetable 
tissue  for  a  considerable  time  in  water  rendered  faintly  alkaline  with 
soda;  the  softened  mass  is  then  rubbed  on  a  sieve  under  a  current  of 
water,  which  washes  out  the  starch -granules;  the  washings  are  allowed 
to  deposit  the  starch,  which,  after  washing  by  decantation,  is  dried  at  a 
low  temperature. 

Starch  is  a  white  powder,  having  a  peculiar  slippery  feel,  but  it  some- 
times appears  in  short  columnar  masses.  The  granules  of  starch  have  a 
similar  appearance  from  whatever  source  they  are  obtained,  yet  those 
from  different  kinds  of  plants  differ  sufficiently  to  allow  of  their  distinc- 
tion by  microscopic  examination.  They  are  rounded  or  egg-shaped 
masses,  having  in  the  centre  or  toward  one  end  a  spot,  called  the  hilum, 
around  which  are  a  series  of  concentric  lines,  indicating  the  junctions  of 
the  various  layers  of  which  the  granules  are  composed — these  markings 
varying  in  character  and  distinctness  in  different  plants.  The  main  char- 
acters of  the  principal  kinds  of  starch  are  given  in  the  table  on  next  page. 

Starch  is  not  altered  by  exposure  to  air,  from  which,  however,  it  ab- 
sorbs moisture;  commercial  dried  starch  contains  eighteen  per  cent,  of 
moisture,  of  which  it  loses  eight  per  cent,  in  vacuo,  and  the  remaining 
ten  per  cent,  when  heated  to  145°.  It  is  insoluble  in  alcohol,  ether,  cold 
acids,  and  cold  water.  If  fifteen  to  twenty  parts  of  water  be  gradually 
heated  with  one  part  of  starch,  the  granules  swell  at  about  55°,  and  at 
80°  they  have  reached  thirty  times  their  original  dimensions;  their  struc- 


AMYLOSES. 


311 


ture'is  no  longer  distinguishable,  and  -they  form,  by  their  agglutination 
with  each  other,  a  translucent,  gelatinous  mass,  commonly  known  as 
starch  paste;  in  this  state  the  starch  is  said  to  be  hydrated,  and,  if  boiled 
with  much  water  and  the  liquid  filtered,  a  solution  of  starch  passes 
through,  which  is  opalescent  from  the  suspension  in  it  of  undissolved 
particles.  Dilute  solutions  of  the  alkalies  produce  the  same  effects  on 
starch  in  the  cold  as  does  hot  water.  Hydrated  starch  is  dextrogyrous, 


CHARACTERS  OP  STARCH-GRANULES. 


From 

Average  size  in 
millimetres. 

Shape. 

Hilum. 

Rings. 

Tous  les  mois 

.0939  —  .0469 

Oval  

j 
Ex.  ... 

In.  F.  R. 

Curcuma  arrow-root 

.0304—  .0609 

Irreg.  oval.  . 

'EX.  ft... 

In.  Cl. 

Maranta  arrow-root      .... 

.01     —  .07 

Ovoid  

Central.  . 

Natal  arrow-root  

.0375—  .0327 

Ovoid  

Ex  

Cl. 

Potato  

.0376—  .0686 

Circ.  ovate  . 

Central.  . 

Cl. 

Ginger 

.0376  — 

Ovoid  ...    . 

Cl  

Galangal 

.0342  —  .  .    . 

Ovoid  

Cl  

Ft. 

Calumba. 

.0469—  .  .    . 

Pear  

Cl  

Ft.  C. 

Orris-root  

.028  —  

Elongated  . 

Ft  

Turmeric 

0376— 

Oval  .  . 

Cl  

In.  Cl. 

Bean 

0343— 

Oval  

Stellate  . 

Ft. 

Pea. 

.0177  —  .0282 

Oval  

Stellate  . 

Ft. 

Lentil  .... 

.0282  — 

Oval  

Linear  .  . 

Ft. 

Pepper  .  . 

.005  —  .0005 

Polygonal.  . 

JNutrneo* 

014  

Pentagonal. 

Ft. 

Dari 

0188  

Hexagonal 

Ft, 

Maize        .  .  . 

0188  — 

Round  .... 

Ft. 

Wheat  

.0022—  .216 

Round  .... 

Inv  

Inv. 

Barley  

.0185—  .07 

Round  .... 

Inv  

Inv. 

Rye  .  . 

.0375  —  .0022 

Round  .... 

Inv  

Inv. 

Chestnut  

.0022  —  .022 

Elliptic.. 

Inv  

Inv. 

Acorn  .... 

0188  

Round  .  .    . 

Ex  

Inv. 

Saofo  .  . 

0282  066 

Oval  

Ex  

Ft. 

Tapioca  

0188  —  .014 

Conical.  .  .  . 

Ex  

Arum  arrow-root  

.014  —  ... 

Truncated.  . 

Ex  

Ft. 

Oat  

0094 

Polyhedral. 

Tahiti  arrow-root  

.019  —  .0094 

Truncated.  . 

Stellate  . 

Rice  

0076  —  005 

Polygonal.  . 

Stellate  . 

Ex.=excentric;  In.  ^incomplete;  F.  =fine;  R.  =  regular;  Ft.  — faint; 
Cl.= clearly  denned;  C.  =  complete;  In  v.  =  in  visible. 

When  subjected  to  dry  heat,  the  granules  of  starch  swell  and  burst; 
at  200°  it  is  converted  into  dextrin;  at  230°  it  forms  a  brownish  yellow 
fused  mass,  composed  principally  of  pyrodextrin.  Hydrated  starch  is 
converted  into  dextrin  by  heating  with  water  at  160°,  and,  if  the  action 
be  prolonged,  the  new  product  is  changed  to  glucose. 


312 


GENERAL    MEDICAL    CHEMISTRY. 


If  starch  be  ground  up  with  dilute  sulphuric  acid,  after  about  half  an 
hour  the  mixture  gives  only  a  violet  color  with  iodine  (see  below);  if  now 
the  acid  be  neutralized  with  chalk  and  the  filtered  liquid  evaporated,  it 
yields  a  white,  granular  product,  which  differs  from  starch  in  being  sol- 
uble in  water,  especially  at  50°,  and  in  having  a  lower  rotary  power, 
[a]D=  +211°.  If  the  action  be  prolonged,  the  value  of  [a]D  continues  to 
sink  until  it  reaches  +73,7°,  when  the  product  consists  of  a  mixture  of 
dextrin  and  glucose.  Concentrated  nitric  acid  dissolves  starch  in  the 
cold,  forming  a  nitro-product  called  xylodin  or  pyrofoam,  which  is  insol- 
uble in  water,  soluble  in  a  mixture  of  alcohol  and  ether;  explosive.  Hy- 
drochloric and  oxalic  acids  convert  starch  into  glucose.  When  starch  is 
heated  under  pressure  to  120°  with  stearic  or  acetic  acid,  compounds  are 
formed  which  seem  to  be  ethers,  arid  to  indicate  that  starch  is  the  hydrate 
of  a  trivalent,  oxygenated  radical,  (C6H7O2)'".  Tannic  acid  produces  in 
cold  solutions  of  starch  a  precipitate,  soluble  at  50°,  and  deposited  on 
cooling.  Potash  and  soda  in  dilute  solutions  convert  starch  into  the  sol- 
uble modification  mentioned  above. 

A  dilute  solution  of  iodine  produces  a  more  or  less  intense  blue-violet 
color  with  starch,  either  dry,  hydrated,  or  in  solution,  the  color  disappearing 
on  the  application  of  heat,  and  returning  on  cooling;  if  to  a  solution  of 
starch,  blued  by  iodine,  a  solution  of  a  neutral  salt  be  added,  there  sep- 
arates a  blue,  flocculent  deposit  of  the  so-called  iodide  of  starcJt.  Iodine 
renders  starch  soluble  in  water,  and  a  soluble  iodized  starch  is  obtained 
by  triturating  together  nine  parts  of  starch,  two  parts  water,  and  one  part 
iodine;  the  mixture  is  then  heated  over  the  water-bath  for  two  hours, 
cooled,  and  precipitated  bv  the  addition  of  the  proper  quantity  of  alcohol. 

The  amount  of  starch  contained  in  food  vegetables  varies  from  about 
five  per  cent,  in  turnips  to  8(J  per  cent,  in  rice,  as  will  be  observed  in  the 
following  table: 

COMPOSITION  OF  VEGETABLE  FOODS. 


Nitrogen- 
ized  matter. 

Starch. 

Dextrin, 
etc. 

Cellu- 
lose. 

Fat. 

Mineral 
matter. 

Carbo- 
hydrate. 

Water. 

Vegetable 
fibre,  etc. 

Authority. 

Wheat,  hard  .  .     . 

22.75 

19.50 
20.0 
15.25 
12.65 
12.50 
12.96 
14.39 
1250 
7.55 
14.45 
10.80 
8.10 
12.60 
13.10 
22.86 
19.0 
80.80 
29.C5 
25.50 
23.80 
25.20 
2.50 
2.10 
1.50 
1.30 
1.10 
1.20 

58.62 
65.07 
63.80 
70.05 
76.51 
64.65 
66.43 
60.59 
67.55 
88.65 

6490 
5680 
600 
48.30 
55.85 
55.70 
58.70 
56.0 
20.0 
18.80 
16.05 
8.40 
9.60 
5.10 

9.50 
7.60 
8.0 
7.0 
6.05 
14.90 
10.0 
9.25 
4.0 
1.0 

1.09 
3.20 
10.20 
6.10 
5.80 
2.10 

3.50 
3.0 
3.10 
8.0 
2.80 
3.10 
4.75 
7.06 
5.90 
1.10 

3.50 

3.0 
1.05 
2.09 
3.50 
2.40 
1.04 

0.45 

2.61 
|2.12 
i2.25 
11.95 
1.87 
2.25 
2.76 
5.50 
8.80 
0.80 
1.25 
2.0 
1.60 
6.60 
3.0 
5.74 
5.0 
1.90 
2.0 
2.80 
2.10 
2.60 
0.11 
0.20 
0.30 
0.20 
0.50 

3.02 
2.71 
2.85 
2.75 
2.12 
2.60 
3.10 
3.25 
1.25 
0.90 
1.60 
1.70 
2.30 
3.0 
2.50 
5.05 

3.50 
3.65 
3.20 
2.10 
2.30 
1.26 
0.70 
2.60 
1.0 
1.0 
0.60 

68.'48 
70.50 
51.00 
63.80 

14.22 
15.0 
37.0 
15.0 
13.0 

16.0 
12.50 

8.40 
9.90 
8.30 
11.50 
74.0 
750 
67.50 
83.0 
82.0 
91.0 

9^53 

i.io 

Pay  en. 
Payen. 
Payen. 
Payen. 
Payen. 
Payen. 
Payen. 
Payen. 
Payen. 
Payen. 
Payen. 
Letheby. 
Letheby. 
Letheby. 
Payen. 
Voelcker. 
Voelcker. 
Payen. 
Payen. 
Payen. 
Payen. 
Payen. 
Payen. 
Letheby. 
Payen. 
Letheby. 
Letheby. 
Letheby. 

Wheat  hard 

Wheat,  hard  . 

Wheat,  semi-hard.. 
"Wheat,  soft 

Rye  

Barley  

Oats  

Maize  . 

Rice  

Flour  

Flour. 

Bread  

Oatmeal  

Buckwheat  .... 

Quinoa  seeds. 

Quinoa  flour  

Horse-bean  .... 

Broad  bean  .  .  . 

"White  bean  .. 

Peas,  dried 

Lentils    

Potato  

Potato 

Sweet  potato  
Carrots...   . 

Parsnip  

Turnip  . 

AMYLOSES.  313 

Starch  has  not  been  found  in  the  animal  economy  outside  of  the  ali- 
mentary canal,  in  which,  as  a  prerequisite  to  its  absorption,  it  must  be 
converted  into  dextrin  and  glucose.  This  change  is  partially  effected  by 
the  action  of  the  saliva,  more  rapidly  with  hydrated  than  with  dry  starch, 
and  more  rapidly  with  the  saliva  of  some  animals  than  that  of  others,  those 
of  man  and  of  the  rabbit  acting  much  more  quickly  than  those  of  the  horse 
and  dog.  The  greater  part  of  the  starch  taken  with  the  food  passes  into 
the  small  intestine  unchanged;  here,  under  the  influence  of  the  pancreatic 
ferment,  the  most  complete  transformation  into  glucose,  and  of  a  portion 
into  lactic  and  butyric  acids,  takes  place.  If,  however,  the  diet  is  abnor- 
mally rich  in  starch,  a  portion  is  wasted,  passing  out  unchanged  in  the 
fasces. 

Glycogen. — This  interesting  body,  which  has  been  the  subject  of 
much  discussion,  was  discovered  by  Cl.  Bernard  in  the  liver,  and  subse- 
sequently  in  the  placenta;  it  has  also  been  found  to  exist  in  white  blood- 
corpuscles,  pus-cells,  young  cartilage-cells,  in  many  embrionic  tissues,  and 
in  muscular  tissue.  During  the  activity  of  muscles  the  amount  of  glyco- 
gen  which  they  contain  is  diminished,  and  that  of  sugar  increased. 

It  is  best  obtained  from  the  liver;  the  organ  is  removed  as  quickly  as 
possible  after  death,  ground  or  cut  into  small  pieces,  which  are  immedi- 
ately thrown  into  boiling  water;  it  should  not  be  subjected  to  prolonged 
boiling,  but,  the  water  being  poured  off,  the  pulp  is  expressed  and  the 
united  liquids  filtered  and  evaporated  over  the  water-bath  to  a  small 
bulk;  the  cooled  solution  is  precipitated  with  glacial  acetic  acid,  or,  bet- 
ter, with  alcohol;  the  precipitate  is  collected,  redissolved  in  water;  the 
solution  filtered  through  animal  charcoal,  and  again,  after  concentration 
if  necessary,  precipitated  by  alcohol. 

Pure  glycogen  is  a  snow-white,  floury  powder;  amorphous,  tasteless, 
and  odorless;  soluble  in  water,  insoluble  in  alcohol  and  ether;  in  water  it 
swells  up  at  first,  and  forms  an  opalescent  solution,  which  becomes  clear 
on  the  addition  of  potash.  According  to  Hoppe-Seyler,  its  solutions  are 
dextrogyrous  to  about  three  times  the  extent  of  those  of  glucose. 

Dilute  acids,  ptyalin,  pancreatin,  extract  of  liver-tissue,  blood,  dias- 
tase, and  albuminoids  convert  glycogen  into  a  sugar  having  all  the  prop- 
erties of  glucose.  Cold  nitric  acid  converts  it  into  xyloidin;  on  boiling, 
into  oxalic  acid.  Its  solutions  dissolve  cupric  hydrate,  which  is,  how- 
ever, not  reduced  on  boiling.  Iodine  colors  glycogen  wine-red. 

Concerning  the  method  of  formation  of  glycogen  in  the  economy,  but 
little  is  known  with  certainty;  there  is  little  room  for  doubting,  however, 
that  while  the  bulk  of  the  glycogen  found  in  the  liver  results  from  mod- 
ification of  the  carbohydrates,  it  may  be  and  is  produced  from  the  al- 
buminoids as  well.  The  ultimate  fate  of  glycogen  is  undoubtedly  its 
transformation  into  sugar  under  the  influence  of  the  many  substances 
existing  in  the  body  capable  of  provoking  that  change. 

Dextrin,  British  gum,  a  substance  resembling  gum  arabic  in  appear- 
ance and  in  many  properties,  is  obtained  by  one  of  three  methods:  1st, 
by  subjecting  starch  to  a  dry  heat  of  175°,  known  as  the  baking  process; 
2d,  by  heating  starch  with  dilute  sulphuric  acid  to  90°  until  a  drop  of 
the  liquid  gives  only  a  wine-red  color,  neutralizing  with  chalk,  filtering, 
concentrating^  precipitating  with  alcohol;  the  product  so  obtained  almost 
always  contains  glucose;  3d,  by  the  action  of  diastase  (infusion  of  malt) 
upon  hydrated  starch;  as  soon  as  the  starch  is  dissolved  the  liquid  must 
be  rapidly  heated  to  boiling  to  prevent  saccharification.  The  product  is 
also  usually  contaminated  with  glucose. 


314  GENERAL   MEDICAL   CHEMISTRY. 

Dextrin  is  a  colorless,  or  yellowish,  amorphous  powder,  soluble  in  water 
in  all  proportions,  forming  syrupy  liquids;  when  obtained  by  evaporation 
of  its  solution,  it  forms  masses  resembling  gum  arabic  in  appearance. 
Dextrogyrous,  [a]  D  =  +  138.88°. 

Nitric  acid  oxidizes  dextrin,  not  to  mucic  acid,  as  it  does  the  gums, 
but  to  oxalic  acid;  a  mixture  of  nitric  and  sulphuric  acids  converts  it 
into  a  dinitro-compound.  Dextrin  reduces  the  cupro-potassic  solutions 
at  85°.  By  iodine  it  is  colored  light  wine-red. 

Dextrin  has  been  found  to  exist  in;  the  blood,  lungs  and  other  organs 
of  carnivora  and  herbivora,  and  in  the  contents  of  the  intestine. 

Inulin — Helenin — Dahlinin — Menyanthin — a  substance  resembling 
starch,  obtained  from  the  roots  of  certain  vegetables;  it  differs  from  starch 
in  being  converted  by  prolonged  contact  with  boiling  water  into  a  Isevogy- 
rous,  uncrystallizable  sugar;  in  being  itself  Isevogyrous,  [«]n  =— 34.  4° 
(?),  in  not  being  colored  blue  by  iodine,  and  in  reducing,  when  heated,  in 
the  presence  of  ammonia,  the  salts  of  copper  and  silver. 

Tunicin,  a  cellulose-like  substance  which  constitutes  the  organic 
portion  of  the  mantle  of  certain  molluscs.  It  withstands  the  action  of 
reagents  better  than  cellulose,  but  may  be  converted  into  a  sugar  by  sul- 
phuric acid. 

Cellulose —  Cellulin — Lignin — forms  the  basis  of  all  vegetable  tis- 
sues; it  exists,  almost  pure,  in  the  pith  of  elder  and  of  other  plants,  in  the 
purer,  unsized  papers,  in  cotton,  and  in  the  silky  appendages  of  certain 
seeds.  Cotton,  freed  from  extraneous  matter  by  boiling  with  potash,  and 
afterward  with  dilute  hydrochloric  acid,  yields  pure  cellulose. 

It  is  a  white  material,  having  the  shape  of  the  vegetable  structure 
from  which  it  was  obtained;  insoluble  in  the  usual  neutral  solvents,  but 
soluble  in  the  deep  blue  liquid  obtained  by  dissolving  copper  in  ammonia 
in  contact  with  air. 

By  the  action  of  reagents  upon  cellulose,  as  paper  and  cotton,  several 
valuable  products  are  obtained. 

Vegetable  parchment,  or  parchment  paper,  a  tough  material,  possess- 
ing all  the  valuable  properties  of  parchment,  is  made  by  immersing  un- 
sized paper  for  an  instant  in  moderately  strong  sulphuric  acid,  washing 
thoroughly,  and  drying. 

Nitro -cellulose.  By  the  action  of  nitric  acid  upon  cellulose,  cotton, 
three  different  products  of  substitution  may  be  obtained:  mononitro-cel- 
lulose,  soluble  in  acetic  acid,  insoluble  in  a  mixture  of  ether  and  alcohol; 
dinitro-cellulose,  insoluble  in  acetic  acid,  soluble  in  a  mixture  of  ether 
and  alcohol;  trinitro- cellulose,  soluble  in  both  the  above  solvents.  Pro- 
ducts known  as  gun-cotton  or  pyroxylin,  composed  of  varying  proportions 
of  these  three  derivatives,  are  obtained  for  use  in  the  arts.  When  gun-cot- 
ton is  required  as  an  explosive  agent,  the  process  is  so  managed  that  the 
product  shall  contain  the  greatest  possible  proportion  of  trinitro-cellu- 
lose,  the  most  readily  inflammable  of  the  three.  When  required  for  the 
preparation  of  collodion  for  use  in  medicine  or  in  photography,  dinitro- 
cellulose  is  the  most  valuable.  To  obtain  this,  a  mixture  is  made  of  equal 
weights  of  nitric  and  sulphuric  acids  (of  each  about  five  times  the  weight 
of  the  cotton  to  be  treated);  in  this  the  cotton  is  immersed  and  well 
stirred  for  about  three  minutes,  after  which  it  is  well  stirred  in  a  large 
vessel  of  water,  washed  with  fresh'  portions  of  water  until  the  washings 
are  no  longer  precipitated  by  barium  chloride,  and  dried.  Collodion  is 
a  solution  of  dinitro-cellulose  in  a  mixture  of  three  volumes  of  ether  and 
one  volume  of  alcohol. 


BENZENE.  315 

Gums  are  substances  of  unknown  constitution,  existing  in  plants; 
amorphous;  soluble  in  water,  insoluble  in  alcohol;  converted  into  glucose 
by  boiling  with  dilute  sulphuric  acid. 

Lichenin  is  obtained  from  various  lichens  by  extraction  with  boiling 
water,  forming  a  jelly  on  cooling;  it  is  oxidized  to  oxalic  acid  by  nitric 
acid;  is  colored  yellow  by  iodine;  and  is  precipitated  from  its  solutions 
by  alcohol. 

Arabin  is  the  soluble  portion  of  gum  arabic  and  gum  Senegal — Aca- 
cia (U.  S.  P.) — in  which  it  exists  in  combination  with  potassium  and 
sodium.  To  separate  arabin,  gum  arabic  is  dissolved  in  water  acidulated 
with  hydrochloric  acid,  and  precipitated  by  alcohol.  It  is  a  white,  amor- 
phous, tasteless  substance,  which  is  not  colored  by  iodine;  is  oxidized  by 
nitric  acid  to  mucic  and  saccharic  acids;  is  converted  by  sulphuric  acid 
into  a  non-fermentable  sugar,  arabinose ;  and  has  the  composition, 
OnH,0010  +  l  Aq. 

Bassorin  constitutes  the  greater  part  of  gum  tragacanth;  it  is  in- 
soluble in  water,  but  swells  up  to  a  jelly  in  that  fluid. 

Cerasin  is  an  insoluble  gum  exuded  by  cherry-  and  plum-trees;  water 
acts  upon  it  as  upon  bassorin. 


FIFTH  SERIES  OF  HYDROCARBONS. 

SERIES  CnH2n_6. 

The  hydrocarbons  of  this  series  are  the  starting-points  from  which 
the  major  part  of  that  numerous  and  important  class  of  substances  usually 
classed  as  aromatic  are  obtainable  or  derivable.  Those  of  the  series  at 
present  known  are: 


Benzene. . .  C6H6  . .  boils  at  80.4C 
Toluene  . . .  C7H8  . .  boils  at  110.3' 
Xylene  ....  C8H10  . .  boils  at  142.0C 


Cumene  . . .  C9Hia  . . .  boils  at  151.4C 
Cymene  . .  .  C10H14  . .  boils  at  175.0C 
Laurene  .  „ .  C,,H,.  .  boils  at  188.  Oc 


Benzene. 

Benzol— phenyl  hydride — C6H6  (not  to  be  confounded  with  the  com- 
mercial benzine,  a  mixture  of  hydrocarbons  of  the  series  CnH2n+2,  ob- 
tained from  petroleum). — This  important  substance,  which  may  be  con- 
sidered as  the  basis  of  all  the  aromatic  compounds,  was  discovered  by 
Faraday  in  1825,  among  the  products  of  the  distillation  of  the  fatty  oils. 

It  does  not  exist  in  nature,  but  is  produced  in  a  great  number  of  re- 
actions. It  is  obtained  by  one  of  two  methods,  according  as  it  is  required 
chemically  pure  or  mixed  with  other  substances. 

To  obtain  it  pure,  recourse  must  be  had  to  the  decomposition  of  one 
of  its  derivatives,  benzoic  acid;  this  substance  is  intimately  mixed  with 
three  parts  of  slacked  lime,  and  the  mixture  heated  to  dull  redness  in  an 
earthenware  retort  connected  with  a  well-cooled  receiver;  the  upper  layer 
of  distilled  liquid  is  separated,  shaken  with  potassium  hydrate  solution, 
again  separated,  dried  by  contact  with  fused  calcium  chloride,  and  redis- 
tilled over  the  water-bath. 

For  use  in  the  arts,  and  for  most  chemical  purposes,  benzene  is  ob- 
tained from  coal-  or  gas-tar,  an  exceedingly  complex  mixture,  containing 
some  forty  or  fifty  substances,  among  which  are: 


316 


GENERAL    MEDICAL    CHEMISTEY. 


HYDROCARBONS. 
Benzene.  Acenaphthalene. 

Toluene. 
Xylene. 
Cumene. 
Cymene. 


Naphthalene. 


Fluorene. 

Anthracene. 

Retene. 

Chrysene. 

Pyrene. 


ACIDS. 
Carbolic. 
Cresylic. 
Phlorylic. 
Rosolic. 
Oxyphenic. 

BASES. 
Pyridine.           Iridoline. 
Aniline.              Cryptidine. 
Picoline.            Acridine. 
Lutidine.           Coridine. 
Collidine.           Rubidine. 
Leucoline.         Viridine. 

By  a  primary  distillation  of  coal-tar  the  most  volatile  constituents,  in- 
cluding benzene,  are  separated  as  light-oil;  this  is  washed,  first  with  sul- 
phuric acid,  and  then  with  caustic  soda,  and  afterward  redistilled;  that 
portion  being  collected  which  passes  between  80°  and  85°.  This  is  the 
commercial  benzene,  a  product  still  contaminated  with  the  higher  homo- 
logues  of  the  same  series,  from  which  it  is  almost  impossible  to  separate 
it,  but  whose  presence  is  rather  advantageous  than  otherwise  to  the  prin- 
cipal use  to  which  benzol  is  put — the  manufacture  of  aniline  dyes. 

Benzene  is  a  colorless,  mobile  liquid,  having,  when  pure,  an  agreeable 
odor;  sp.  gr.  0.86  at  15°;  crystallizing  at  -f-4.50;  boiling  at  80.5°;  very 
sparingly  soluble  in  water,  soluble  in  alcohol,  ether,  and  acetone.  It  dis- 
solves iodine,  sulphur,  phosphorus,  resins,  caoutchouc,  gutta-percha,  arid 
almost  all  the  alkaloids.  It  is  inflammable,  and  burns  with  a  luminous, 
smoky  flame. 

Benzene  unites  with  chlorine  or  bromine  to  form  products  of  addi- 
tion, or  of  substitution;  the  corresponding  iodine  compounds  can  only  be 
obtained  by  indirect  methods.  Sulphuric  acid  combines  with  benzene  to 
form  a  neutral  substance,  sulpfiO'benzide,  when  the  anhydrous  acid  is 
used,  and  phenyl-sulphurous  acid  with  the  ordinary  sulphuric  acid. 

The  action  of  nitric  acid  upon  benzene  is  of  great  commercial  inter- 
est; if  fuming  nitric  acid  of  sp.  gr.  1.52  be  slowly  added  to  benzene,  a 
reddish  liquid  is  formed;  from  which,  on  the  addition  of  \vater,  a  reddish 
yellow  oil  separates,  and  is  purified  by  washing  with  water  and  with  so- 
dium carbonate  solution,  drying  and  rectifying;  this  oily  material  is  mono- 
nitro-benzene  (see  pp.  319,  333).  If  benzol  be  boiled  with  fuming  nitric 
acid,  or  if  it  be  dropped  into  a  mixture  of  nitric  and  sulphuric  acids,  so 
long  as  the  fluids  mix,  a  crystalline  product,  dinitro-benzene,  is  formed. 

The  constitution  of  benzene,  the  nucleus  of  the  aromatic  compounds, 
differs  much  in  character  from  that  of  the  hydrocarbons  of  the  series  hith- 
erto considered,  and  is  of  importance  in  connection  with  the  formation  of 
its  numerous  derivatives.  Writing  the  molecular  formulae  of  the  sixth  of 
each  of  the  first  three  series  (the  constitution  of  those  of  the  terebenthene 
series  is  still  doubtful)  we  have: 


First  Series. 


Second  Series. 

CEEH, 


Thk-d  Series. 


=  H 


UH. 


C 


U-H 


O.HM 


C.H., 


BENZENE.  317 

and  those  of  the  second  term   (the  first  being  necessarily  absent  in  the 
second  and  third  series): 

C  -—  H3  C  =  Ha  C  —  Jti 


O.H.  C,H4  O.H. 


It  will  be  observed  that  in  each  of  these  the  chain  of  carbon  atoms  is 
an  open  one,  and  that  the  series  differ  in  this,  that  in  the  first,  each  of  the 
atoms  of  carbon  exchanges  with  its  neighbor  a  single  valence;  in  the 
second,  two  neighboring  carbon-atoms  exchange  two  valences  between 
them;  and  that  in  the  third  there  is  an  exchange  of  three  valences  be- 
tween two  neighboring  carbon-atoms.  And,  further,  that  in  terms  above 
the  second  in  the  first  two  series,  and  the  third  in  the  third  series,  supe- 
rior homologues  may  be  considered  as  formed  by  interpolation  of  CH3  in 
the  chain  of  the  one  next  below. 

In  the  case  of  benzene,  Kekule  has  advanced  the  theory,  according  to 
which  alone  the  formation  of  the  benzene  derivatives  can  be  explained, 
and  against  whose  adoption  no  reason  based  upon  experiment  has  been  ad- 
vanced; that  the  carbon  atoms  of  the  benzene  molecule  are  arranged,  not 
in  an  open,  but  a  closed  chain,  that  they  exchange  with  each  other  alter- 
nately one  and  two  valences,  and  that  consequently  the  molecular  for- 
mula of  benzol  is: 

H 

A 


C 

;         .       A 

Further,  that  the  superior  homologues  of  benzene  are  derived  from  it 
by  the  substitution  of  CH3  for  H,  and  that  all  the  derivatives  of  benzol 
are  formed  by  such  substitution  of  a  group  or  groups  for  an  atom  or  atoms 
of  hydrogen,  in  such  a  way  that  they  all  contain  one  or  more  groups  of 
six  atoms  of  carbon  arranged  as  above: 

H  H 

d  i 


H-C        C-C  =  H,  H-C        C-O-H 

I         II  I         II 

H-C       C-H  H-C        C-H 

Y  V 


i 


Toluene.  Phenol  (carbolic  add). 


318 


GENERAL    MEDICAL    CHEMISTRY. 


H 

Nitrobenzene.  Amido-benzene  (aniline). 


Toluene. 

Toluol — Methyl-benzene — C6H5,CH3 — exists  in  the  products  of  distilla- 
tion of  wood,  coal,  etc.,  and  as  one  of  the  constituents  of  commercial  ben- 
zene; in  Rangoon  tar,  a  native  mineral  oil.  It  has  been  formed  synthetic- 
ally by  acting  upon  a  mixture  of  monobromo-benzene  and  methyl  iodide 
with  sodium.  It  is  obtained,  with  considerable  difficulty,  by  fractional 
distillation  from  coal-tar. 

It  is  a  colorless  liquid,  having  a  peculiar  odor,  differing  somewhat  from 
that  of  benzene;  boils  at  110.3°;  does  not  solidify  at  —20°;  sp.  gr.  0.872 
at  15°;  almost  insoluble  in  water,  soluble  in  alcohol,  ether,  carbon  disul- 
phide.  It  burns  with  a  bright,  but  very  smoky  flame. 

It  yields  a  number  of  derivatives  similar  to  those  of  benzene,  among 
which  may  be  mentioned  nitro-toluene  and  toluidine,  the  homologues  of 
nitro-benzene  and  aniline,  which  accompany  those  substances  in  the  com- 
mercial products;  cresylol,  the  superior  homologue  of  carbolic  acid,  and 
benzylic  alcohol. 

Xylene — Xylol — Dimethyl-benzene — C6H^  (CH3)S — accompanies  its  in- 
ferior homologues  in  coal-tar.  When  pure  it  is  a  liquid  of  an  aromatic 
odor;  sp.  gr.  0.865  at  20°;  boils  at  142°;  insoluble  in  water,  soluble  in 
ether,  benzene,  etc.,  sparingly  soluble  in  alcohol. 

There  are  three  isomeric  substances  having  this  composition,  and 
differing  in  the  position  in  which  the  substituted  CH3  groups  are  placed. 
Each  of  these  corresponds  to  a  series  of  derivatives  parallel  to  those  of 
benzene. 

Cumene — Cumol — Propyl-benzene — C6HB  (C3H7) — is  obtained  by  dis- 
tilling a  mixture  of  cuminic  acid  and  lime,  as  benzene  is  prepared  from 
benzoic  acid.  It  is  a  limpid  liquid,  having  a  strong  aromatic  odor;  boils 
at  151.4°;  insoluble  in  water,  very  soluble  in  alcohol  and  ether. 

There  are  several  isomeres  of  this  substance,  among  which  are  pseudo- 
cumene,  or  trimethyl-benzene,  C6H3  (CH8)3,  and  mesitylene,  or  methyl-ethyl- 
benzene,  CflH4  (OH3)(C2Hf.);  each  corresponding  to  a  series  of  derivatives. 

Cymene —  Cymol — there  are  many  isomeres,  of  which  one  exists  ready 
formed  in  essence  of  cumin,  and  in  hemlock.  It  is  a  colorless,  oily  liquid; 
has  an  odor  of  lemon;  sp.  gr.  0.857  at  16°;  boils  at  175°;  insoluble  in  water, 
but  readily  soluble  in  alcohol,  ether,  and  essential  oils. 

Laurene — is  an  imperfectly  studied  body,  obtained  by  the  decompo- 
sition of  camphor  by  zinc  chloride.  It  is  a  colorless  liquid,  boiling  at  188°; 
sp.  gr.  0.887  at  10°. 


PHENOLS.  319 


Nitro-derivatives. 

The  products  of  this  class  are  quite  numerous,  among  them  the  only 
one  calling  for  consideration  here  is: 

Nitrobenzene — nitro-benzol — mono-nitro-benzene — essence  of  Mir- 
bane — 06H5(NO2) — this  important  substance,  whose  production  lies  at  the 
root  of  the  aniline  industry,  was  discovered  by  Mitscherlich,  and  is  formed 
by  the  action  of  nitric  acid  upon  benzene. 

Benzol  is  slowly  added  to  fuming  nitric  acid,  or  to  a  mixture  of  nitric 
and  sulphuric  acids,  care  being  taken  to  agitate  the  mixture  and  to  pre- 
vent elevation  of  temperature  ;  the  nitro-benzene  formed  is  decanted, 
repeatedly  washed  with  solution  of  sodium  carbonate  and  with  water. 
The  result  of  this  process  is  sufficiently  pure  for  industrial  uses;  if  re- 
quired in  a  state  of  greater  purity,  it  may  be  distilled — a  process,  however, 
attended  with  considerable  loss. 

Nitro-benzene  is  a  yellowish  liquid;  has  a  sweet  taste  and  a  pronounced 
odor  of  bitter  almonds;  sp.  gr.  1.209  at  15°;  boils  at  213°;  almost  insolu- 
ble in  water,  very  soluble  in  alcohol  and  ether. 

Chlorine  and  bromine  do  not  attack  it  at  ordinary  temperatures. 
Concentrated  sulphuric  acid  dissolves  it,  and,  at  the  boiling  temperature, 
decomposes  it;  boiled  with  fuming  nitric  acid,  it  is  converted  into  binitro- 
benzene;  with  ordinary  nitric  or  sulphuric  acid,  it  may  be  distilled  un- 
changed. It  is  attacked  by  potash  with  difficulty. 

The  most  important  reaction  of  nitro-benzene  is  that  with  reducing 
agents;  a  great  number  of  which  convert  it  into  aniline  (q.  v.). 

Under  the  names  essence  of  mirbane  and  artificial  essence  of  bitter 
almonds,  this  substance  has  been  used  in  perfumery  to  a  considerable  ex- 
tent— a  use  which  cannot  be  too  strongly  condemned,  as  nitro-benzol  is,  as 
well  in  the  form  of  vapor  as  in  that  of  liquid,  an  active  poison.  When 
taken  internally,  even  in  a  dose  of  a  few  drops,  it  has  caused  death  in 
several  instances,  although  recovery  has  followed  the  taking  of  a  con- 
siderably larger  dose.  Inhalation  of  its  vapor,  even  when  largely  diluted 
with  air,  produces  headache,  drowsiness,  difficulty  of  respiration,  cardiac 
irregularity,  more  or  less  loss  of  muscular  power,  convulsions,  coma. 
Obviously,  the  frequent  inhalation,  even  in  small  quantities,  of  a  substance 
such  as  this,  is  to  be  avoided. 

Nitro-benzol  can  be  distinguished  from  benzoic  aldehyde  by  sulphuric 
acid,  which  does  not  color  the  former;  and  by  the  action  of  acetic  acid 
and  iron  filings,  which  convert  nitro-benzene  into  aniline,  whose  presence 
is  indicated  by  the  reactions  on  p.  333. 


Phenols. 

The  hydrocarbons  of  this  series,  unlike  those  previously  considered, 
form  by  substitution  two  distinct  series  of  hydrates,  which  differ  from  each 
other  materially  in  their  properties.  The  terms  of  one  of  these  series 
possess  all  the  functions  of  the  alcohols,  and  are  therefor  known  as  the 
aromatic  alcohols  (see  p.  323).  The  terms  of  the  other  series  differ  in 
function  from  any  substance  thus  far  considered,  and  are  known  as 
phenols,  the  difference  between  them  and  the  aromatic  alcohols  being 


320  GENERAL   MEDICAL    CHEMISTRY. 

probably  due  to  the  fact  that  in  the  phenols  the  OH  is  directly  attached 
to  a  carbon  atom,  while  in  the  alcohols  it  is  substituted  for  an  atom  of 
hydrogen  of  a  substituted  hydrocarbon  group,  thus: 

H  H 

C 


H-C        0-CH,  H-C'       C-CHOH 

I         H  I          II 

H-C        C-OH  H-C        C-H 

v  v 


Benzylic  phenol.  Benzylic  alcohol. 

The  phenols  differ  from  the  alcohols  in  many  particulars:  in  not  fur- 
nishing by  oxidation  corresponding  aldehyds  and  acids;  in  not  dividing 
into  water  and  hydrocarbon  under  the  influence  of  dehydrating  agents; 
in  not  reacting  witli  acids  to  form  ethers;  in  combining  to  form  directly 
products  of  substitution  with  chlorine,  bromine  and  nitrosyl;  and  in  form- 
ing with  metallic  elements  compounds  more  stable  than  similar  compounds 
of  the  true  alcohols.  In  short,  the  phenols  appear  to  have,  besides  an 
alcoholic  function,  more  or  less  of  the  function  of  acids. 


Phenol. 

Phenyl  hydrate — Phenic  acid — Carbolic  acid — Acidum  carbolicum 
(U.  S.,  Br.)  C6H6OH — exists  in  considerable  quantity  in  coal-  and  wood- 
tar,  and  in  small  quantity  in  castoreum,  and  possibly  in  urine. 

It  is  formed  in  a  number  of  reactions:  1st,  by  fusing  sodium  phenylsul- 
phite  with  an  excess  of  alkali;  2d,  by  heating  phenyl  iodide  with  potas- 
sium hydrate  to  320°;  3d,  by  heating  together  salicylic  acid  and  quick- 
lime; 4th,  by  total  synthesis  from  acetylene;  5th,  by  dry  distillation  of 
benzoin. 

The  source  from  which  it  is  exclusively  obtained  is  coal-tar,  or  rather 
that  portion  of  the  product  of  distillation  of  coal-tar  which  passes  over  be- 
tween 150°  and  200°.  This  is  treated  with  a  saturated  solution  of  potash 
containing  undissolved  alkali;  a  solid  phenate  is  formed,  which  is  dissolved 
in  hot  water;  the  liquid  is  allowed  to  separate  into  two  layers,  the  lower 
of  which  is  drawn  off  and  neutralized  with  hydrochloric  acid;  the  phenol 
rises  to  the  surface,  is  separated,  washed  with  water,  dried  over  calcium 
chloride,  redistilled,  crystallized  at  —10°,  and  the  crystals  drained. 

Pure  phenol  crystallizes  in  long,  colorless,  prismatic  needles,  fusible  at 
35°,  boiling  at  187°.  It  has  a  peculiar,  well-known  odor,  and  an  acrid, 
burning  taste;  very  sparingly  soluble  in  water,  readily  soluble  in  alcohol 
and  in  ether;  sp.  gr.  1.065  at  18°;  neutral  in  reaction.  On  contact  with 
the  skin  or  with  mucous  surfaces,  it  produces  a  white  stain;  it  coagulates 
albuminoids,  and  is  a  powerful  antiseptic. 


PHENOL.  321 

Phenol  is  capable  of  distillation  without  decomposition,  and  at  a  red 
heat  is  only  partially  decomposed,  with  formation  of  a  small  quantity  of 
naphthalin.  On  contact  with  damp  air  it  absorbs  moisture  to  form  a 
hydrate,  which  crystallizes  in  six-sided  prisms,  fusible  at  16°,  which  loses 
its  water  at  187°.  Vapor  of  phenol  is  reduced  to  benzene  when  heated 
with  zinc-filings. 

It  combines  with  sulphuric  acid  to  form  sulpho-conjugate  acids 
(phenylsulphuric  acids).  With  concentrated  hydriodic  acid  at  280°  it  yields 
benzene.  Nitric  acid  converts  it  into  nitro-derivatives,  differing  with  the 
concentration  of  the  acid  used;  with  an  acid  of  36°  B.  it  forms  trinitro- 
phenic  or  picric  acid  (q.  v.).  When  heated  with  sulphuric  and  oxalic 
acids,  it  forms  a  colored  substance  known  as  corallin  or  rosolic  acid;  this 
is  a  mixture  from  which  several  beautiful  pigments,  aurin,  peonin, 
azulin,  and  phenicin,  are  obtained. 

Phenol  may  be  recognized  by  the  following  reactions:  1st,  its  peculiar 
odor;  3d,  the  formation  of  the  yellow  picric  acid  with  nitric  acid  of  36°  B. ; 
3d,  the  production  of  a  blue  or  green  color  when  treated  with  a  small 
quantity  of  ammonium  hydrate  and  a  trace  of  solution  of  a  hypochlorite; 
4th,  a  lilac  color  produced  on  the  addition  of  a  small  quantity  of  ferric 
sulphate;  5th,  a  yellowish  white  precipitate  with  bromine  water;  6th,  pre- 
cipitation of  albuminoids.  Of  these  reactions,  3d,  4th,  and  5th  are  very 
delicate. 

Toxicology. — The  use  of  carbolic  acid  in  medicine,  both  for  external 
use  as  one  of  the  most  valuable  of  antiseptics,  and  for  internal  adminis- 
tration, has  of  late  years  become  widely  extended.  The  energy  of  its 
caustic  action  upon  living  tissues,  and  of  its  power  of  coagulation  of  the 
albuminoids,  render  it  very  actively  injurious  when  taken  internally,  and 
although  its  odor  prevents,  in  a  great  measure,  its  ingestion  by  mistake, 
or  its  administration  with  murderous  intent;  yet  such  cases  have  occurred, 
and  instances  in  which  it  is  taken  suicidally  are  becoming  exceedingly 
common.  Woodman  and  Tidy  cite  twenty-one  cases  of  poisoning  by 
phenol  occurring  during  the  years  of  1868  to  1873,  among  which  there 
was  but  one  recovery,  the  doses  taken  being  usually  one  to  two  ounces, 
a  quantity  certainly  much  greater  than  the  minimum  lethal  dose;  in  one 
instance  death  followed  the  application  of  carbolic  acid  to  a  wound. 

When  this  poison  has  been  taken,  the  mouth  is  whitened  by  its  caustic 
action;  there  is  a  marked  odor  of  carbolic  acid  in  the  breath.  The  acid 
is  eliminated  by  the  urine,  partly  unchanged,  and  partly  in  the  form  of 
colored  derivatives,  which  communicate  to  the  urine  a  greenish,  brownish, 
or  even  black  colour;  biliary  acids  are  also  usually  present. 

The  treatment  consists  in  the  administration  of  albumen  (white  of  egg) 
and  of  emetics. 

To  detect  phenol  in  the  urine,  that  liquor  must  not  be  distilled  with 
sulphuric  acid,  as  sometimes  recommended,  as  it  contains  normally  sub- 
stances which  by  such  treatment  yield  carbolic  acid.  The  best  method  is 
that  of  Landolt,  which  consists  in  adding  an  excess  of  bromine  water  to 
about  500  c.c.  of  the  urine;  on  standing  some  hours,  a  yellowish  precipi- 
tate collects  at  the  bottom  of  the  vessel;  this  is  removed,  washed,  and 
treated  with  sodium  amalgam,  when  the  characteristic  odor  of  phenol  is 
developed.  From  other  parts  of  the  body,  phenol  may  be  recovered  by 
acidulating  with  tartaric  acid;  distilling;  extracting  the  distillate  by 
shaking  with  ether;  evaporating  the  ethereal  solution;  extracting  the 
residue  with  a  small  quantity  of  water,  and  applying  to  this  solution  the 
tests  described  above. 
21 


322  GENERAL    MEDICAL    CHEMISTRY. 

Trinitrophenol — Picric  acid — Trinitrophenic  acid — C6H2  (NO.,)., 
OH. — This  substance,  the  method  of  whose  formation  has  been  given 
above,  is  derived  from  phenol  by  the  substitution  of  three  groups  (NO.,) 
for  three  atoms  of  hydrogen;  it  is  the  only  one  of  the  numerous  substi- 
tution products  of  phenol  which  is  of  sufficient  medical  interest  for  con- 
sideration here. 

It  crystallizes  in  brilliant,  yellow,  rectangular  plates,  or  in  six-sided 
prisms;  it  is  odorless,  and  has  an  intensely  bitter  taste,  whence  its  more 
common  name  (from  TriKpos=. bitter);  it  is  acid  in  reaction;  sparingly 
soluble  in  water,  very  soluble  in  alcohol,  ether,  and  benzene;  it  fuses  at 
122.5°,  and  may,  if  heated  with  caution,  be  sublimed  unchanged;  but,  if 
heated  suddenly  or  in  quantity,  it  explodes  with  vio)ence. 

Trinitrophenol  behaves  as  a  monobasic  acid,  forming  salts,  which  are 
for  the  most  part  soluble,  yellow,  crystalline,  and  decompose  with  explo- 
sion when  heated. 

The  presence  of  picric  acid  is  detected  by:  1st,  its  intensely  bitter 
taste;  2d,  its  alcoholic  solution  when  shaken  with  a  potassium  salt  gives 
a  yellow  crystalline  precipitate;  3d,  an  ammoniacal  solution  of  cupric 
sulphate  gives  a  green,  crystalline  precipitate;  4th,  glucose  heated  with  a 
dilute  alkaline  solution  of  picric  acid,  communicates  to  it  a  blood-red 
color;  5th,  warmed  with  an  alkaline  solution  of  potassium  cyanide,  an  in- 
tense red  color  is  produced  (the  same  effect  is  produced  by  ammonium 
sulphydrate);  6th,  unbleached  wool,  immersed  in  boiling  solution  of  picric 
acid,  is  dyed  yellow.  Nos.  1,  3,  5  and  6  are  quite  delicate. 

Picric  acid  stains  animal  tissues  yellow,  and  is  used  for  that  purpose 
by  histologists.  It  is  largely  used  for  dyeing;  is  fraudulently  added  to 
beers  to  render  them  bitter;  and  is  of  value  in  toxicological  analysis,  as 
it  precipitates  the  alkaloids  from  their  solutions. 

When  taken  internally  in  overdose,  it  acts  as  a  poison;  it  may  be 
separated  from  animal  fluids  or  ffom  beer  by  evaporating  to  a  syrup,  ex- 
tracting with  95  per  cent,  alcohol,  acidulated  with  sulphuric  acid;  filter- 
ing; evaporating;  and  applying  the  above-mentioned  tests  to  a  solution 
of  the  residue. 


Cresylol. 

Cresol —  Cresylicacid — Benzy  lie  phenol —  Cresylic  phenol — C6H4  (CH3) 
OH — accompanies  phenol  in  coal-  and  wood-tars,  from  which  it  may  be 
obtained  by  fractional  distillation;  it  is  more  readily  obtained  pure  from 
toluene. 

When  pure  it  is  a  crystalline  solid,  fusible  at  34.5°;  as  usually  met 
with,  however,  it  is  a  liquid,  which  does  not  solidify  at  —18°,  and  boils 
at  203°;  it  has  an  odor  of  creasote.  Its  properties,  decompositions  and 
products  resemble  those  of  phenol. 

Creasote  is  a  complex  mixture,  containing  phenol,  cresylol,  creasol, 
C8H}0O2,  and  other  substances  obtained  from  wood-tar,  and  formerly  ex- 
tensively used  as  an  antiseptic.  It  is  an  oily  liquid,  colorless  when 
freshly  prepared,  but  becoming  brownish  on  exposure  to  light;  it  has  a 
burning  taste  and  a  strong,  peculiar  odor;  its  specific  gravity  is  variously 
stated  from  1.037  to  1.087  at  20°;  it  boils  at  203°,  and  does  not  solidify  at 
-27°. 

Crude  phenol  is  often  substituted  for  creasote;  the  two  substances 
may  be  distinguished  by  the  following  characters: 


AROMATIC    ALCOHOLS. 


323 


PHENOL. 

Soluble  in  commercial  glycerin. 
Precipitates  nitro-celiulose  from  collodion. 
Gives  a  brown  color  with  ferric  chloride 

and  alcohol. 
Gives  a   violet  color  with  ferric  chloride 

and  ammonium  hydrate. 


CREASOTE. 

Insoluble  in  commercial  glycerin. 

Does  not  precipitate  collodion. 

Gives  a  green  color  with  ferric  chloride 

and  alcohol. 
Gives  a  green  color,  passing  to  brown,  with 

ferric  chloride  and  ammonium  hydrate. 


Xenols — Xylenols — C6H3  (CHS)2OH. — Theoretically  there  are  six  pos- 
sible xenols,  derivable  from  corresponding  xylenes;  of  these,  four  have 
been  thus  far  obtained  by  the  general  methods  of  obtaining  the  phenols. 
None  is  of  practical  interest. 

Thymol — Cy  my  lie  phenol — C6H(CH3)4OH,  exists,  accompanying  cy- 
mene  and  thymene,  C,0H]6,  in  essence  of  thyme,  from  which  it  was  first  and 
is  still  obtained;  the  essence  contains  about  one-half  its  weight  of  thymol, 
which  is  separated  by  agitation  with  a  concentrated  solution  of  caustic 
soda;  separation  of  the  alkaline  liquid,  which  is  diluted  and  neutralized 
with  hydrochloric  acid;  thymol  separates  and  is  purified  by  rectification 
at  230*. 

It  crystallizes  in  large,  transparent,  rhombohedral  tables;  has  a  pep- 
pery taste  and  an  agreeable,  aromatic  odor;  it  fuses  at  44°  and  boils  at 
230°;  is  sparingly  soluble  in  water,  very  solublq  in  alcohol  and  ether; 
with  the  alkalies  it  forms  definite  compounds,  which  are  very  soluble  in 
water.  Its  reactions  are  very  similar  to  those  of  phenol. 

Thymol  is  an  excellent  disinfecting  and  antiseptic  agent,  and  one  of 
the  best  of  embalming  materials;  possessing  the  advantage  over  phenol  of 
having  itself  a  pleasant  odor,  while  that  of  phenol  is  disagreeable  to 
most  persons. 


Aromatic  Alcohols. 


The  alcohols  corresponding  to  this  series  of  hydrocarbons  have  the 
same  composition  as  the  corresponding  phenols,  from  which  they  differ  in 
constitution  and  in  having  the  function  of  true  alcohols  (see  p.  150). 
The  first  of  the  series  is: 

Benzylic  alcohol— Benzole  alcohol— Benzyl  hydrate — C6H§(CHa 
OH) — does  not  exist  in  nature,  and  is  of  interest  chiefly  as  corresponding  to 
two  important  compounds,  benzoic  acid  and  benzoic  aldehyde  (oil  of  bit- 
ter almonds).  It  is  obtained  by  the  action  of  potassium  hydrate  upon  oil 
of  bitter  almonds,  or  by  slowly  adding  sodium  amalgam  to  a  boiling  solu- 
tion of  benzoic  acid. 

It  is  a  colorless  liquid;  sp.  gr.  1.05  at  14.4°;  boils  at  206.5°;  has  an 
aromatic  odor;  is  insoluble  in  water,  soluble  in  all  proportions  in  alcohol, 
ether,  and  carbon  disulphide 

By  oxidation  it  yields,  first,  benzoic  aldehyde,  C6HB  (COH);  and  after- 
ward, benzoic  acid,  C?H5  (COOH).  By  the  same  means  it  may  be  made 
to  yield  products  similar  to  those  obtained  from  the  alcohols  of  the  satu- 
rated hydrocarbons. 

The  remaining  alcohols  of  this  series  are: 

Xylylic  alcohol. .  . . C6H6  (CH2-CH2OH). 

Cumylic  alcohol C6H5  (CH2-CH2-CH2OH). 

Cymylic  alcohol CeH5  (CHa-CH3-CHa~CH,OH). 


324  GENERAL   MEDICAL    CHEMISTRY. 


Diatomic  Aromatic  Hydrates. 

There  are  three  classes  of  these  substances,  viz.  :  Diatomic  phenols, 
diatomic  alcohols,  and  alphenols,  which  last  are  substances  having  a  mixed 
function  of  alcohol  and  phenol,  thus: 

H  v    H  H 

i  ,3  i 

c  .,'r  •          c  c 

H-C        C-OH  H-C      'C-CHaOH  H-C        C-CHaOH 

II         i  II         I  II         I 

H-C        C-OH  H-C        C-CHaOH          H-C        C-OH 


0  C  C 

I  I  I 

H  H  H 

Hydroquinone  Toluyl  glycol  Saligenin 

(diatomic  phenol).  (diatomic  alcohol).  (alphenol). 

Phenols  —  Oxyphenols.  —  There  exist  three  different  compounds  of  the 
composition  06H6Oa. 

Pyrocatechin,  a  crystalline  solid,  fusible  at  112°,  boiling  at  240°,  has 
a  powerful  odor;  soluble  in  water  and  alcohol;  obtained  by  the  dry  dis- 
tillation of  kino  and  catechu. 

Resorcin,  colorless,  prismatic  crystals,  fusible  at  110°,  boiling  at 
270°;  obtained  by  the  action  of  potash  on  galbanum,  assafetida,  etc. 

Hydroquinone,  transparent,  colorless  prisms,  fusible  at  177.5°;  solu- 
ble in  water,  alcohol,  and  ether;  obtained  by  the  action  of  reducing  agents 
on  quinone. 


. 

Quinone,  CeH4      |  —  is  formed  by  the  action  of  oxidizing  agents  on 


quinic  acid  (q.  v.);  it  crystallizes  in  long,  transparent  needles,  fusible 
at  115.7°;  very  soluble  in  water,  alcohol,  and  ether;  very  volatile,  emitting 
irritating  vapors  at  all  temperatures;  its  solution  stains  the  skin  brown. 

Orcin,  C7H802,  the  superior  homologue  of  hydraquinone,  is  obtained 
from  lichens  of  the  genus  Hocella.  It  forms  white,  crystalline  needles, 
fusing  at  86°,  boiling  at  280°  —  287°;  sweet  in  taste;  soluble  in  water, 
alcohol,  and  ether.  Anhydrous  orcine  absorbs  dry  ammonia,  forming  large, 
colorless  crystals,  which,  although  permanent  in  a  dry  vacuum,  rapidly 
absorb  moisture  from  the  air  and  are  converted  into  orcein,  C,H7N03,  the 
coloring  matter  of  orchil  and  litmus. 
/CH2OH 

Saligenin,    C6H4  —  is  an  alphenol,  i.e.,  a  substance  partly 

XOH 

alcohol  (by  the  group  CH2OH)  and  partly  phenol.  It  is  obtained  from 
salicine  (q.  v.)  in  large,  tabular  crystals;  quite  soluble  in  alcohol,  water 
and  ether.  Oxidizing  agents  convert  it  into  salicylic  aldehyde,  which  by 
further  oxidation  yields  salicylic  acid. 

/CHaOH 

Toluyl   glycol.  CeH.  —  the    only   one   of   the   diatomic, 

\CH2OH 
aromatic  alcohols  at  present  known;   has  been  recently  obtained  by  Gri- 


ACIDS   CORRESPONDING   TO   THE   AROMATIC   HYDRATES.    325 

maux,  by  saponifying  the  corresponding  chloride  or  bromide;  it  forms 
opaque,  crystalline  needles;  very  soluble  in  water.  By  oxidation  with 
potassium  dichromate  and  sulphuric  acid,  it  yields  terephthalic  acid.  (See 
below.) 

Triatomic  Aromatic  Hydrates. 

The  only  compounds  of  this  class  at  present  known  with  certainty  are 
two  isomeric  triatomic  phenols,  which  probably  owe  the  differences  in 
properties  existing  between  them  to  a  different  placing  of  the  OH  groups. 
They  are  phloroglucin  and  pyrogallol. 

Phloroglucin,  C6H3  (OH)8 — is  obtained  by  the  action  of  potash  upon 
phloretin,  quercitriii,  maclurin  (see  Glucosides),  catechin,  kino,  etc.  It 
crystallizes  in  rhombic  prisms,  containing  2  Aq.;  is  very  sweet;  very  sol- 
uble in  water,  alcohol,  and  ether. 

Pyrogallol — Pyrogattic  acid — C6H3  (OH)3 — is  formed  when  gallic  acid 
(q.  v.)  is  heated  to  200°;  it  crystallizes  in  white  needles;  neutral  in  reac- 
tion; very  soluble  in  water;  very  bitter;  fuses  at  115°;  boils  at  210°; 
poisonous.  Its  most  valuable  property  is  that  of  absorbing  oxygen  from 
the  air,  for  which  purpose  it  is  used  in  the  laboratory  in  the  form  of  a 
solution  of  potassium  pyrogallate. 


Acids  Corresponding  to  the  Aromatic  Hydrates. 

The  acids,  possibly  derivable  from  benzene  by  the  substitution  of 
(COOH),  or  of  (COOH)  and  (OH),  for  atoms  of  hydrogen,  would  form,  were 
they  all  known,  a  great  number  of  series;  there  are,  however,  compar- 
atively few  of  them  which  have  been  as  yet  obtained,  although  the  num- 
ber of  acid  series  known  is  greater  than  that  of  corresponding  alcohols. 
Each  series  of  mono-  and  diatomic  alcohols  furnishes  a  corresponding 
series  of  acids;  thus: 

C6H5-CH2OH  C61 

Benzoic  alcohol.  Toluyl  glycol.  Saligenin. 

n  „  /COOH 


«<\COOH 

Benzoic  acid.  Terephthalic  acid.  Salicylic  acid. 

There  are  still  a  number  of  other  series  of  acids  possibly  derivable 
directly  from  benzene,  without  speaking  of  substituted  acids  of  more  com- 
plex nature;  of  these,  however,  the  majority  are  wanting. 

By  the  progressive  substitution  of  groups  (COOH)  for  atoms  of  hy- 
drogen in  benzene,  we  may  obtain  six  series  of  acids,  five  of  which  have 
been  isolated: 

CflH&  (COOH)  —  CnHan_8O;, Benzoic  series. 

C6H4  (COOH)  -CrtHan_10O4 Phthalic  series. 

C6H3  (COOH)8-CttH2W_1206 Trimellitic  series. 

C8H2  (COOH)4-CnH2n_1408 Prehnitic  series. 

C6H  (COOH)5  _CnH2n_16010 Wanting. 

C6  (COOH)6      -  C«Han_18Oia Mellitic  series. 


326 


GENERAL    MEDICAL    CHEMISTRY. 


The  alphenols,  containing  a  single  group  (OH),  are  at  present  repre- 
sented by  a  single  series: 

C6H4  (OH)  (COOH) -CJIan_803— Salicylic  series. 

Corresponding  to  the  unknown  alphenols,  containing  a  greater  num- 
ber of  (OH)  groups,  there  are  at  present  but  two  series  of  acids  known: 


and 


CeH8  (OH),  (COOH)-CnH^_8O4— Yeratric  series, 
C6Ha  (OH)3  (COOH) -CnHan_8O6— Gallic  series. 


In  each  of  these  series  the  basicity  is,  as  usual,  equal  to  the  number  of 
groups  (COOH). 


Benzole  Series,  CnHan_8Oa. 

The  acids  of  this  series  (which  are,  as  the  formula  above  indicates, 
monobasic)  at  present  known  are: 


Benzoic  acid C7H8O3 

Toluic  acid CgH8O2 

Xyiic  acid C»Hi0O2 


Cumic  acid Ci0H12O2 

aCymic  acid CiiHi4O3 


Benzole  acid,  C6HB  (COOH) — one  of  the  earliest  known  of  organic 
acids,  having  been  obtained  by  sublimation  from  benzoin.  It  exists  ready 
formed  in  benzoin,  tolu  balsam,  castoreum,  and  several  resins  (see  p.  297), 
it  does  not  exist  in  animal  nature,  so  far  as  is  at  present  known;  in  those 
situations  in  which  it  has  been  found,  it  has  resulted  from  decomposition 
of  hippuric  acid  (q.  v.),  or  has  been  introduced  from  without.  When 
taken  in  moderate  doses,  it  does  not  pass  out  in  its  own  form,  but  is  con- 
verted into  hippuric  acid;  in  excessive  doses  a  portion  is  eliminated,  un- 
changed, in  the  urine. 

Benzoic  acid  is  obtained  by  one  of  two  processes:  1st.  For  use  in  med- 
icine, it  is  extracted  from  benzoin,  which  is  boiled  for  some  hours  with 
milk  of  lime;  the  solution  of  calcium  benzoate  so  formed  is  filtered  off 
and  decomposed  with  hydrochloric  acid;  the  precipitated  acid  is  washed 
and  purified,  either  by  recrystallization  from  boiling  water,  or  by  sublima- 
tion; in  the  latter  case  the  crude  acid  is  heated  in  a  porcelain  dish,  over 
which  is  placed  a  sheet  of  filter-paper,  and  over  that  a  cone  of  bristol- 
board,  which  acts  as  a  condenser.  The  process  formerly  followed,  by  direct 
sublimation  of  benzoin,  is  not  as  advantageous.  3d.  For  use  in  the  arts, 
benzoic  acid  is  obtained  from  the  urine  of  herbivorous  animals;  this  is 
boiled  with  hydrochloric  acid,  and  treated  with  milk  of  lime,  the  calcium 
salt  is  decomposed,  and  the  liberated  acid  purified  as  above.  The  acid 
prepared  by  this  process  retains  tenaciously  an  odor  of  urine,  which  may 
be  removed  to  a  great  extent  by  distilling  with  a  little  benzoin. 

Benzoic  acid  is  formed  in  a  variety  of  reactions,  among  others  by  syn- 
thesis from  benzene;  this  is  converted  into  its  monobrorno-derivative, 
which  is  mixed  with  sodium  and  treated  with  carbon  dioxide: 


C.H6Br 

Monobromo- 


+     Na. 


Sodium. 


CO,     = 

Carbon 
dioxide. 


C7H502Na 

Sodium 
benzoate. 


NaBr 

Sodium 
bromide. 


BENZOIC    SERIES.  327 

a  general  reaction,  by  which  several  other  acids  are  obtained  from  corres- 
ponding hydrocarbons. 

Pure  benzoic  acid  crystallizes  in  white,  transparent,  pearly  plates  or 
needles;  odorless  (the  pharmaceutical  product  usually  has  a  faint  odor  of 
benzoin);  acid  in  taste;  fuses  at  122°;  sublimes  at  145°;  boils  at  240°; 
sparingly  soluble  in  cold  water,  soluble  in  twelve  parts  of  boiling  water, 
very  soluble  in  alcohol  and  ether. 

Dilute  nitric  and  chromic  acids  do  not  attack  benzoic  acid.  It  dis- 
solves in  ordinary  sulphuric  acid,  and  may  be  precipitated  from  the  solu- 
tion, unchanged,  by  the  addition  of  water;  Nordhausen  sulphuric  acid 
converts  it  into  sulphobenzoic  acid.  Fuming  nitric  acid  forms  with  it 
nitrobenzoic  acid;  and  a  mixture  of  fuming  nitric  and  sulphuric  acids 
binitrobenzoic  acid.  Under  the  influence  of  sodium  amalgam,  it  yields 
benzylic  alcohol  and  other  products.  Distilled  with  an  excess  of  lime  or 
baryta,  it  yields  carbon  dioxide  and  benzene. 

The  salts  of  benzoic  acid  are  all  soluble,  those  of  the  heavy  metals  less 
so  than  those  of  the  alkaline  metals. 

The  radical  of  benzoic  acid  (C7H6O)',  is  known  as  benzoyl;  it  enters 
into  a  number  of  compounds  similar  to  those  of  acetyl  (C  H  O)';  thus  we 
have  a  hydride  C7H5OH;  a  chloride,  C7HBOC1;  an  amide,  C7H&ONHa. 

Intimately  connected  with  benzoic  acid  is  Hippuric  acid — Benzylgly- 
cocol — Benzyl-amido-acetic  acid — C9H9NO3 — a  constant  constituent  of 
the  urine  of  the  herbivora.  In  human  urine,  with  normal  food,  it  exists  in 
small  quantity;  with  a  purely  vegetable  diet,  its  elimination  is  greatly  in- 
creased, as  it  is  also  after  the  administration  of  benzoic  acid,  and,  to  a  less 
degree,  in  diabetes  mellitus  and  in  chorea.  The  amount  of  hippuric  acid 
eliminated  under  normal  circumstances  by  man  varies  from  0.29  gram  to 
2.84  grams  in  twenty-four  hours. 

Hippuric  acid  is  extracted  from  the  urine  of  the  horse,  cow,  etc. ;  this 
is  concentrated  to  a  syrup  and  treated  with  two  to  three  times  its  bulk  of 
hydrochloric  acid;  the  highly  colored  deposit  of  hippuric  acid  is  converted 
into  sodium  hippurate;  the  solution,  decolorized  with  a  little  hypochlorite 
solution,  and  again  precipitated  with  hydrochloric  acid;  if  required  pure,  it 
must  be  further  decolorized  by  boiling  with  animal  charcoal,  and  recrystal- 
lization. 

It  crystallizes  in  colorless,  transparent  prisms;  odorless;  faintly  bitter; 
sparingly  soluble  in  cold  water,  less  so  in  the  presence  of  hydrochloric 
acid,  more  so  in  the  presence  of  hydrodisodic  phosphate,  very  soluble  in 
boiling  water  and  in  alcohol,  insoluble  in  ether;  fuses  at  130°;  boils  at 
240°;  at  a  slightly  higher  temperature  it  is  decomposed,  with  formation  of 
benzoic  and  hydrocyanic  acids. 

To  understand  the  reactions  of  hippuric  acid,  a  knowledge  of  its  con- 
stitution is  necessary.  It  has  been  long  known  that  hippuric  acid  may 
be  decomposed  into  glycocol  (see  page  208)  »nd  benzoic  acid.  Later,  by 
the  action  of  nitrous  acid  upon  hippuric  acid,  an  acid  having  the  constitu- 
tion of  glycolic  acid,  in  which  the  alcoholic  hydrogen  is  replaced  by 
benzoyl  (see  above)  was  obtained,  and  designated  as  benzogtycolic  acid. 
Finally,  hippuric  acid  has  been  obtained  synthetically  by  the  action  of 
benzoyl  chloride  upon  silver  glycolamate: 

C2H,(NH2)02Ag     +    C7H5OC1    =    C9H9NO3     +     AgCl 

Silver  glycolamate.  Benzoyl  Hippuric  Silver 

chloride.  aoid.  chloride. 

And  again,  hippuric  apid  has  been  obtained  by  the  action  of  benzamide 


328  GENERAL   MEDICAL    CHEMISTRY. 

upon  chloracetic  acid.  Now,  glycocol  is  derivable  from  glycolic  acid  by 
the  substitution  of  NHa  for  OH;  or  from  chloracetic  acid  by  the  substitu- 
tion of  NHa  for  01: 

CH3OH  CH8C1  CH,(NH2) 

COOH  COOH  COOH 

Glycolic  acid.  '-CljloracetJc  acid.          Amido-acetic  acid  (glycocol). 

The  foregoing  decompositions  and  syntheses  show  that  hippuric  acid 
is  glycocol  in  which  the  radical  benzoyl  has  been  substituted  for  one  H  of 
the  group  NH2;  it  is  therefor: 

CHS(NH[C,H,0]) 


io 


)OH 

Benzyl-glycocol  or  benzyl  amido-acetic  acid. 

Hippuric  acid  dissolves  unchanged  in  concentrated  hydrochloric  acid; 
on  boiling  the  solution  it  is  decomposed  into  benzoic  acid  and  glycocol; 
the  same  decomposition  is  effected  by  dilute  sulphuric,  nitric,  and  oxalic 
acids,  and  also  by  a  ferment  developed  in  putrefying  urine.  Concentrated 
sulphuric  acid  forms  a  brown  solution  with  hippuric  acid,  which,  on  the 
application  of  heat,  gives  off  sulphur  dioxide  and  benzoic  acid.  Nascent 
hydrogen  produces  a  number  of  derivatives  from  hippuric  acid,  among 
which  are  benzoic  aldehyde  and  glycocol.  Oxidizing  agents  convert  it 
into  benzoic  acid,  carbon  dioxide,  and  benzamide. 

The  determination  of  hippuric  acid  in  urine  is  a  tedious  process. 
About  a  litre  of  the  urine  is  precipitated  with  baryta  water;  filtered;  the 
excess  of  barium  removed  from  the  filtrate  by  cautious  addition  of  sul- 
phuric acid,  avoiding  an  excess;  the  filtrate  is  neutralized  with  hydro- 
chloric acid  and  evaporated  to  a  syrup;  this  is  extracted  with  alcohol; 
the  alcoholic  solution  decanted  and  evaporated  over  the  water-bath;  the 
residue  repeatedly  washed  with  ether;  dissolved  in  warm  water  and 
heated  with  a  little  milk  of  lime;  filtered,  the  filtrate  decomposed  with 
hydrochloric  acid;  the  crystals  which  separate  are  washed  with  a  small 
quantity  of  water,  dried,  and  weighed.  It  is  usually  necessary  to  redis- 
solve  the  acid  in  water,  decolorize  with  animal  charcoal,  and  reprecipitate 
before  weighing. 

The  characters  of  hippuric  acid  are:  1st,  when  heated  in  a  dry  tube,  it 
fuses  and  decomposes,  giving  a  sublimate  of  benzoic  acid  and  an  odor  of 
hydrocyanic  acid  (q.  v.)\  2d,  it  gives  a  brown  precipitate  with  ferric 
salts  (so  do  benzoic  and  succinic  acids);  3d,  when  heated  with  lime,  it 
gives  off  benzene  and  ammonia.  Benzoic  acid,  by  similar  treatment, 
gives  off  benzene,  but  no  ammonia. 

The  remaining  acids  of  the  benzoic  series  are  not  of  medical  interest. 
The  number  of  their  isomeres  is  great. 


Phthalic  Series,  CnH2n_JOO4. 

Phthalic  acid,  C8H6O4,  and  its  isomeres,  terephtJidlic  and  isophtha- 
lic  acids,  are  the  only  ones  of  this  series  at  present  known.  Phthalic 
acid  is  obtained  by  the  action  of  nitric  acid  upon  naphthalene  or  alizarin 


TRIMELLITIC    SEKIES.  329 

(q.  v.).  It  crystallizes  in  white  prisms;'  sparingly  soluble  in  water,  very 
soluble  in  alcohol  and  ether;  it  fuses  at  180°,  and  at  a  higher  temperature 
is  decomposed  into  phthalic  anhydride,  C6H4(CO)2O,  and  water;  by  cau- 
tious heating  it  is  decomposed  into  carbon  dioxide  and  benzoic  acid,  a 
reaction  which  is  utilized  to  obtain  the  last-named  acid. 


Salicylic  Series,  CJI^gO,. 

The  acids  of  this  series  (which  are,  as  indicated  by  the  formula  on  p. 
325,  partly  phenols,  partly  acids)  are  the  following: 


Salicylic  acid C7H«O3 

Anisic  acid C&HbO3 

Phloretic  acid C9H10O3 


Oxycuminic  acid 
Thymotic  acid 


Salicylic  Acid—Oxybenzoic  acid—  C6H4  (OH)  COOH— was  first  ob- 
tained from  essence  of  spiraea,  which  consists  largely  of  salicylic  alde- 
hyde, and  subsequently  from  oil  of  wintergreen  (gaultheria),  which 
contains  methyl  salicylate;  and  also  from  salicine,  a  glucoside  yielding 
salicylic  aldehyde. 

At  present  salicylic  acid  is  obtained  almost  exclusively  by  Kolbe's 
method,  from  phenol.  This  is  fused,  and  while  a  current  of  dry  carbon 
dioxide  is  passed  through  it,  small  portions  of  sodium  are  added;  the  so- 
dium salicylate  thus  formed  is  dissolved  in  water  and  decomposed  with 
hydrochloric  acid,  when  the  liberated  salicylic  acid  is  precipitated. 

It  crystallizes  in  fine  white  needles  (the  pharmaceutical  product  is 
usually  pink) ;  very  sparingly  soluble  in  cold  water,  quite  soluble  in  hot 
water,  alcohol,  and  ether;  it  fuses  at  158°,  and  may  be  distilled  with  but 
slight  decomposition,  if  it  be  pure. 

Chlorine  and  bromine  form  with  it  products  of  substitution.  Fuming 
nitric  acid  forms  with  it  a  nitro-derivative  and,  if  the  action  be  prolonged, 
converts  it  into  picric  acid.  With  ferric  chloride,  its  aqueous  solution  as- 
sumes a  fine  violet  color. 

Salicylic  acid  and  its  salts  (it  is  monobasic,  although  diatomic)  are  ex- 
tensively used  in  medicine,  both  externally  as  antiseptics  and  internally 
in  the  treatment  of  rheumatism,  etc.  It  is  not  without  caustic  properties, 
and  hence,  when  taken  internally,  it  should  be  largely  diluted. 


Trimellitic  Series, 

There  are  no  less  than  three  isomeric  acids  having  the  composition  of 
the  first  term  of  this  series,  all  of  which  are  tribasic: 

Trimellitic  acid,  C6H3  (COOH)3 — obtained  by  heating  Jiydropyromel- 
litic  acid  with  sulphuric  acid,  isophthalic  acid  being  formed  at  the  same 
time;  also  formed  when  rosin  is  oxidized  with  nitric  acid.  Fuses  at  216°. 

Trimesitic  acid — formed  by  the  oxidation  of  mesitylenic  acid /  fuses 
at  a  temperature  above  300°. 

Hemimellitic  acid — formed,  along  with  phthalic  acid,  by  heating  hij- 
dromettophanic  acid  with  sulphuric  acid;  fuses  at  185°. 


330  GENERAL    MEDICAL    CHEMISTRY. 


Prehnitic  Series,  CttH2n_14O8. 

Of  this  series  there  are  also  three  isomerides  of  the  first  term;  all  te- 
trabasic: 

Prehnitic  acid,  C6H2  (COOH)4— fuses  at  237°. 

Pyromellitic  acid- — formed  by  the  distillation  of  mellitic  acid. 

Mellophanic  acid — obtained,  along  .tfith  prehnitic  acid,  by  decompos- 
ing hydromellitic  acid,  CjaHiaOia. 


Mellitic  Series,  CnH2n_18O19, 

is  represented  by  a  single  term,  in  which  the  hydrogen  of  benzene  has 
been  entirely  replaced: 

Mellitic  acid,  C6  (COOH)6 — occurs  in  nature  as  its  aluminium  salt  in 
the  mineral  called  mellite  or  honey  stone.  It  has  also  been  obtained  syn- 
thetically by  oxidizing  charcoal  with  potassium  permanganate  in  alkaline 
solution. 

It  crystallizes  in  colorless  needle's,  readily  soluble  in  water;  sour  in 
taste.  It  withstands  the  action  of  reagents  well,  but  by  distillation  with 
quicklime  is  decomposed  into  benzene  and  carbon  dioxide. 


Gallic  Series,  CnH2n_8O5. 

Gallic  acid,  C6HQ  (OH)3COOH— the  first  term  and  only  representa- 
tive of  the  series,  exists  in  nature  in  certain  leaves,  seeds,  and  fruits.  It 
is  best  obtained  from  gall-nuts  which  contain  its  glucoside,  gallotannic 
acid  (q.  v.).  These  galls  are  moistened  and  kept  at  a  temperature  of  20° 
— 25°,  being  moistened  from  time  to  time,  for  a  month;  the  colored, 
mouldy  mass  is  strongly  expressed  and  the  residue  extracted  with  boiling 
water,  which,  on  cooling,  deposits  crystals  of  gallic  acid.  It  can  be  ob- 
tained from  salicylic  acid. 

It  crystallizes  in  long,  silky  needles;  odorless;  acidulous  in  taste; 
sparingly  soluble  in  cold  water,  very  soluble  in  hot  water  and  in  alcohol; 
its  solutions  are  acid.  When  heated  to  210° — 215°  it  yields  carbon  diox- 
ide and  pyrogallol  (q.  v.).  Its  solution  does  not  precipitate  gelatin,  nor 
the  salts  of  the  alkaloids,  as  does  tannin.  It  forms  four  series  of  salts. 


Aldehydes. 

Benzoic  aldehyde — Benzoyl  hydride — C6H6  (COH) — is  the  main 
constituent  of  oil  of  bitter  almonds,  although  it  does  not  exist  in  the  al- 
monds (see  p.  342) ;  it  is  formed,  along  with  hydrocyanic  acid  arid  glucose, 
by  the  action  of  water  upon  amygdalin.  It  is  also  formed  by  a  number 
of  general  methods  of  producing  aldehydes:  by  the  dehydration  of  ben- 
zylic  alcohol;  by  the  dry  distillation  of  a  mixture  in  molecular  propor- 
tions of  calcium  benzoate  and  formiate;  by  the  action  of  nascent  hydro- 
gen upon  benzoyl  cyanide,  etc. 

It  is  obtained  from  bitter  almonds;  these  are  crushed  and  freed  from 


ALDEHYDES.  331 

fixed  oil  by  expression;  the  cake  is  mixed  with  a  large  quantity  of  water, 
in  which  it  remains  twenty-four  hours,  after  which  the  mixture  is  dis- 
tilled by  steam  heat  as  long  as  the  distillate  has  the  odor  of  bitter  al- 
monds; the  oil  separates  from  the  watery  liquid,  which  still  contains  a 
considerable  quantity  in  solution,  recoverable  by  a  second  distillation. 
This  crude  oil  contains,  besides  benzoic  aldehyde,  hydrocyanic  and  ben- 
zoic  acids  and  cyanobenzoyl;  to  purify  it,  it  is  treated  with  three  to  four 
times  its  volume  of  a  concentrated  solution  of  sodium  bisulphite;  the 
crystalline  mass  is  expressed,  dissolved  in  a  small  quantity  of  water,  and 
decomposed  with  a  concentrated  solution  of  sodium  carbonate — the  treat- 
ment being  repeated,  if  necessary. 

It  is  a  colorless  oil,  having  an  acrid  taste  and  the  odor  of  bitter  almonds; 
sp.  gr.  1.043;  boils  at  179.4°;  soluble  in  thirty  parts  of  water,  and  in  all 
proportions  in  alcohol  and  ether. 

Its  vapor,  passed  through  a  tube  filled  with  fragments  of  pumice  and 
heated  to  redness,  is  decomposed  into  benzene  and  carbon  dioxide.  Oxi- 
dizing agents  convert  it  into  benzoic  acid,  a  change  which  occurs  by 
mere  exposure  to  air.  Nascent  hydrogen  converts  it  into  benzylic  alco- 
hol. With  chlorine  or  bromine  it  forms  benzoyl  chloride  or  bromide. 
Sulphuric  acid  dissolves  it  when  heated,  forming  a  purple-red  color,  which 
turns  black  if  more  strongly  heated. 

When  perfectly  pure,  benzoic  aldehyde  exerts  no  deleterious  action 
when  taken  internally;  owing,  however,  to  the  difficulty  of  completely  re- 
moving the  hydrocyanic  acid,  the  substances  usually  sold  as  oil  of  bitter 
almonds,  ratafia,  and  almond  flavor,  are  almost  always  poisonous,  if  taken 
in  sufficient  quantity.  They  may  contain  as  much  as  ten  to  fifteen  per 
cent,  of  hydrocyanic  acid,  although  said  to  be  "  purified";  the  presence 
of  the  poisonous  substances  may  be  detected  by  the  tests  given  on  page 
340. 

Cuminic  aldehyde,  C9Hn  (COH),  exists,  along  with  a  liquid  hydro- 
carbon, in  cumin-seeds  and  essence  of  cumin,  from  which  it  is  obtained, 
by  fractional  distillation,  in  much  the  same  way  as  benzoic  aldehyde.  It 
is  a  colorless  or  yellowish  oil;  has  a  penetrating  and  disagreeable  odor,  and 
an  acrid,  burning  taste;  sp.  gr.  0.9727  at  13°;  boils  at  220°.  Its  reactions 
are  similar  to  those  of  benzoic  aldehyde. 

Salicylic  aldehyde — Salicyl  hydride — Salicylol — Salicylous  acid— 
C6H4  (OH)  COH — exists  in  the  flowers  of  spiral  ulmaria,  and  is  the  prin- 
cipal ingredient  of  the  essential  oil  of  that  plant.  It  is  best  obtained  by 
oxidizing  salicine  (q.  v.)  with  a  mixture  of  sulphuric  acid  and  potassium 
dichromate. 

It  is  a  colorless  oil;  turns  red  on  exposure  to  air;  has  an  agreeable, 
aromatic  odor,  and  a  sharp,  burning  taste;  sp.  gr.  1.173  at  13.5°;  boils  at 
196.5°;  soluble  in  water,  more  so  in  alcohol  and  ether. 

It  is,  as  we  should  suspect  from  its  origin,  a  substance  of  mixed  func- 
tion, possessing  the  characteristic  properties  of  aldehyde  and  phenol.  It 
produces  a  great  number  of  derivatives,  some  of  which  have  the  charac- 
ters of  salts  and  ethers. 

Anisic  aldehyde,  C6H?CH3  (OH)  COH — obtained  from  the  essence 
of  anis;  is  a  yellowish  liquid;  has  an  aromatic  odor  and  a  burning  taste; 
sp.  gr.  1.09  at  20°;  boils  at  254°;  almost  insoluble  in  water,  readily  soluble 
in  alcohol  and  ether. 


-v 
332  GENERAL    MEDICAL    CHEMISTRY. 

• 

Amines. 
Phenylamines. 

Benzene  may  be  considered  as  being  made  up  of  a  radical  group 
(C6HB)',  united  to  hydrogen;  this  radical  is  known  as  phenyl,  and  benzene 
is,  therefor,  phenyl  hydride,  as  *  marsh-gas  is  methyl  hydride.  The  radi- 
cal, phenyl,  is  capable,  like  methyl,  of  replacing  atoms  of  hydrogen  of 
ammonia  to  form  amines  precisely  similar  in  typical  constitution  to  those 
of  the  univalent  alcoholic  radicals  (see  p.  155);  or  these  amines  may  be 
considered  as  formed  by  the  substitution  of  a  group  NH3  for  an  atom  of 
hydrogen  of  one  molecule  of  benzene,  or  of  (NH)"  for  two  atoms  of 
hydrogen  in  two  molecules,  etc.  : 

H 

' 


X  N 
CHa  (NH3);  H-C          C-NH 

OH8  H-C          C-H 

V 


H 

I 

/ 

X   \    /      \    X  \ 
H-C  C  C  C-H 

I  (I  I  H 

H-C  C  -  H  H  -  C  C-H 

.          v       -v 

r-p       ; -l;  •:•.;••       i 

or  typically: 


Phenylamine. 

These  amines  are,  in  their  turn,  capable  of  forming  a  vast  number  of 
products  of  substitution,  salts,  etc.  Of  the  compounds  of  this  class,  the 
most  important  by  far  is: 

Phenylamine — Amido  -  benzene — Amido  -  benzol — Aniline — Kyanol 

C1  TT   ) 
—  Cristalline —     jr5  [  N. — It  was  discovered  in  1826,  by  Unverdorben, 

among  the  products  of  the  dry  distillation  of  indigo;  later  it  was  found 


AMINES.  333 

to  exist  in  coal-tar;  and,  finally,  Zinin  discovered  the  method  of  obtaining 
it  from  nitro-benzene  which  is  at  present  used.  This  reaction  is  a  reduc- 
tion, consisting  in  the  removal  of  Oa,  and  the  substitution  therefor  of  Ha: 

C6HB  (NO,)  +  3H3  =  C6H5(NH2)  +  2H,O 

Nitrobenzene.  Hydrogen.         Amidobenzene.  Water. 

Aniline  is  now  obtained  in  large  quantities  from  nitrobenzene,  which 
is  mixed  with  acetic  acid,  and  to  the  mixture  iron  turnings  or  borings  are 
gradually  added;  the  nascent  hydrogen  liberated  by  the  action  of  the 
metal  upon  the  acid  being  the  reducing  agent;  the  addition  of  iron  is 
continued  until  a  pasty  mass  is  formed,  which  is  then  neutralized  with 
lime  and  subjected  to  distillation. 

Aniline  is  also  formed  in  other  reactions:  in  small  quantity  when 
phenol  and  ammonia  are  long  heated  together  under  pressure;  by  the  dry 
distillation  of  indigo,  etc. 

When  pure,  aniline  is  a  colorless  liquid;  has  a  peculiar,  aromatic 
odor,  and  an  acrid,  burning  taste;  sp.  gr.  1.02  at  16°;  boils  at  184.8°; 
crystallizes  at  — 8°;  soluble  in  thirty-one  parts  of  cold  water,  soluble  in 
all  proportions  in  alcohol,  ether,  carbon  disulphide,  etc.;  when  exposed 
to  air,  it  turns  brown,  the  color  of  the  commercial  "  oil,"  and,  finally, 
resinifies;  it  is  neutral  in  reaction. 

Its  vapor,  when  heated  to  redness,  is  decomposed  into  carbon,  am- 
monia, ammonium  cyanide,  and  a  complex  brown  liquid.  Oxidizing  agents 
convert  it  into  blue,  violet,  red,  green,  or  black  derivatives.  Chlorine,  bro- 
mine, and  iodine  act  upon  it  violently  to  produce  products  of  substitu- 
tion. Concentrated  sulphuric  acid  converts  it,  according  to  the  conditions, 
into  sulphanilic  or  disulphanilic  acid.  With  acids  it  unites,  after  the 
manner  of  the  ammonias,  without  liberation  of  water  or  hydrogen  to 
form  salts,  most  of  which  are  crystallizable,  soluble  in  water,  and  colorless, 
although  by  exposure  to  air,  especially  if  moist,  they  turn  red. 

The  presence  of  aniline  may  be  detected  by  the  following  characters: 
1st,  on  the  addition  of  a  nitrate  and  of  sulphuric  acid,  a  red  color  is  pro- 
duced; 3d,  cold  sulphuric  acid  does  not  color  it  alone,  on  the  addition  of 
potassium  dichromate,  a  fine  blue  color  is  produced,  which,  on  dilution 
with  water,  passes  to  violet,  and,  if  not  diluted,  to  black  (see  Strychnine); 
3d,  with  calcium  hypochlorite  solution  it  gives  a  violet  color;  4th,  when 
heated  with  cupric  chlorate,  a  deep  black  color  is  produced;  5th,  a  deep 
crimson  color  appears  when  it  is  heated  with  mercuric  chloride. 

Experiments  upon  animals  show  aniline  to  be  an  active  poison  when 
taken  in  the  liquid  form,  or  by  inhalation  of  its  vapor;  its  salts,  however, 
if  pure,  seem  to  be  without  deleterious  action.  The  symptoms  produced 
by  aniline  are  very  similar  to  those  of  nitrobenzene  poisoning. 

Derivatives  of  aniline. — Although  aniline  and  most  of  its  salts  are 
colorless,  some  of  the  most  brilliant  dyes  at  present  in  use  are  produced 
from  them.  We  merely  mention  the  more  prominent: 

Hosaniline  chloride— fuchsine — magenta — a  magnificent  red  dye,  for- 
merly obtained  by  oxidizing  aniline  with  arsenic  acid  and  combining  the 
base  so  formed  with  hydrochloric  acid.  The  difficulty  of  disposing  of  the 
arsenical  refuse  of  this  process,  and  the  deleterious  action  of  the  dyes 
from  which  the  arsenic  had  been  imperfectly  removed,  have  led  to  a 
modification  of  the  process  in  which  nitrobenzene  itself  is  used  as  the 
oxidizing  agent.  The  base,  rosaniline,  is  an  almost  colorless,  crystalline 
compound,  although  its  salts  are  so  brilliantly  colored. 


334  GENERAL    MEDICAL    CHEMISTRY. 

The  dyes  derived  from  rosaniline  are  very  numerous;  prominent 
among  them  are  fuchsine,  rosaniline  chloride,  a  green,  crystalline  sub- 
stance, soluble  in  alcohol,  with  a  beautiful  magenta  color;  Ifofmann's 
violet,  triethyl-rosaniline,  obtained  by  heating  together  rosaniline  and 
ethyl  iodide;  Lyons  blue,  triphenyl-rosaniline  hydrochloride,  obtained  by 
heating  rosaniline  with  an  .excess  of  aniline;  gas  green,  obtained  by 
heating  rosaniline  chloride  with  aldehyde  and  sulphuric  acid;  Paris 
violet,  obtained  by  the  oxidation  of  methyl  aniline. 

Mauvein  is  a  base  whose  sulphate,  obtained  by  mixing  cold  dilute 
solutions  of  potassium  dichromate  and  aniline  sulphate,  is  a  fine,  purple 
dye.  A  blue  dye  is  also  obtained  by  heating  mauvein  with  aniline. 

Aniline  black  is  obtained  by  acting  on  aniline  with  a  mixture  of  cu- 
pric  sulphate  and  potassium  chlorate. 

Saff'ronin  is  a  base  derived  from  commercial  oils,  rich  in  the  superior 
homologues  of  aniline  (toluidines);  its  hydrochlorate  is  largely  used  in 
place  of  safflower  for  dyeing  silks. 


SIXTH  SERIES  OF  HYDROCARBONS. 

CWH2H_, 

This  series  has  at  present  but  two  representatives,  derivable  from 
benzene  by  the  substitution  of  one  lateral  chain  for  an  atom  of  hydrogen. 

Cinnamene — Styrolene —  Cinnamol — Styrol — Liquid  essence  of  sty* 
rax — C8H8 — exists  ready  formed  in  essential  oil  of  styrax;  it  is  also 
formed  by  decomposition  of  cinnamic  acid  (q.  v.),  or,  synthetically,  by  the 
action  of  a  red  heat  upon  pure  acetylene,  a  mixture  of  acetylene  and  ben- 
zene, or  a  mixture  of  benzene  and  ethylene. 

It  is  a  colorless  liquid;  has  a  penetrating  odor,  recalling  those  of  ben- 
zene and  naphthalene,  and  a  peppery  taste;  sp.  gr.  0.928  at  16°;  boils  at 
143°;  soluble  in  all  proportions  in  alcohol  and  water;  neutral  in  reaction. 

Cedrene,  C16H24 — is  the  liquid  hydrocarbon  of  essence  of  Virginia 
cedar;  it  is  a  colorless  liquid,  of  sp.  gr.  0.984  at  14.5°,  and  boils  at  237°. 


Alcohols— SERIES  CnHan_80. 

There  are  but  two  alcohols  of  this  series  known  : 
Cinnyl  alcohol. C9H10O | Cholesterin C26H44O 

Cinnyl  alcohol — Cinnamic  alcohol — Styrolic  alcohol — Styrone — 
Styracone — Peruvine — C9H9OH — is  obtained  by  .distilling  styracine  (see 
below)  with  a  concentrated  solution  of  potash  or  soda. 

It  crystallizes  in  soft,  silky  needles;  has  a  sweet  taste  and  an  odor  of 
hyacinth;  fuses  at  33°;  distils  at  250°;  sparingly  soluble  in  water,  and 
readily  soluble  in  alcohol,  ether,  and  cinnamene. 

Styracine,  or  cinnyl  cinnamate,  exists  in  Peru  balsam  and  in  styrax, 
from  the  latter  of  which  it  is  obtained. 

It  crystallizes  in  prisms,  grouped  in  bundles;  odorless  and  tasteless; 
fuses  at  38°;  insoluble  in  water,  sparingly  soluble  in  cold  alcohol, 


ALCOHOLS.  335 

readily  soluble  in  ether.  When  heated  with  potash  it  is  decomposed, 
liberating  cinnamic  alcohol. 

Cholesteric  alcohol — Cholesterin — C26H43OH. — This  substance,  of 
great  physiological  interest,  is  shown  by  its  reactions  to  be  certainly  an 
alcohol,  and  probably  one  belonging  to  this  series;  although  it  is  usually 
classed  by  physiologists  among  the  fats  for.no  better  reason  than  that  it 
is  greasy  to  the  touch  and  soluble  in  ether. 

It  has  been  found  in  the  animal  economy,  normally  in  the  bile,  blood 
(especially  that  coming  from  the  brain),  nerve-tissue,  brain,  spleen,  sebum, 
contents  of  the  intestines,  meconium  and  fseces;  pathologically  in  biliary 
calculi,  in  the  urine  in  diabetes  and  icterus,  in  the  fluids  of  ascites,  hy- 
drocele,  etc.,  in  tubercular  and  cancerous  deposits,  in  cataracts,  in  ather- 
omatous  degenerations,  and  sometimes,  in  masses  of  considerable  size,  in 
certain  cerebral  tumors.  It  has  also  been  found  to  exist  in  the  vegetable 
world  in  peas,  beans,  olive-oil,  wheat,  etc.  It  has  not  been  obtained  by 
synthesis. 

Cholesterin  is  best  obtained  from  biliary  calculi,  the  lighter-colored 
varieties  of  which  consist  almost  entirely  of  this  substance.  The  calculi 
are  pulverized,  extracted  with  boiling  ether,  the  solution  filtered  hot, 
the  ether  distilled  off,  the  residue  dissolved  in  boiling  alcohol,  and  the 
solution  allowed  to  cool;  the  crystals  which  separate  are  heated  for  some 
time  with  alcohol  containing  a  little  potash;  on  cooling,  crystals  form, 
which  are  finally  washed  with  alcohol  so  long  as  the  washings  are  colored 
or  alkaline,  and  recrystallized  from  ether. 

Cholesterin  crystallizes  with  or  without  water  of  crystallization;  from 
benzol,  petroleum,  chloroform,  or  anhydrous  ether,  it  separates  in  delicate, 
colorless,  silky  needles,  having  the  composition  C26H44O;  from  hot  alcohol, 
or  a  mixture  of  alcohol,  and  ethqr,  it  crystallizes  in  rhombic  plates,  usually 
with  one  obtuse  angle  wanting,  having  its  composition  C26H44O  +  1  Aq. ; 
these  crystals,  transparent  at  first,  become  opaque  on  exposure  to  air, 
from  loss  of  aq.  It  is  insoluble  in  water,  in  alkalies  and  dilute  acids, 
difficultly  soluble  in  cold  alcohol,  readily  soluble  in  hot  alcohol,  ether, 
benzol,  acetic  acid,  glycerin,  and  solutions  of  the  biliary  acids.  It  is 
odorless  and  tasteless.  When  anhydrous  it  fuses  at  145°  and  solidifies 
at  137°;  at  360°  in  vacuo  it  distils  unchanged;  sp.  gr.  1.046.  It  is  las- 
vogyrous,  [a]D  =  31.6°  in  any  solvent. 

It  combines  readily  with  the  volatile  fatty  acids.  From  its  solution 
in  glacial  acetic  acid  a  compound  having  the  composition  C26H44O,C2H4Oa 
separates  in  fine  curved  crystals,  which  are  decomposed  on  contact  with 
water  or  alcohol;  when  heated  with  acids  under  pressure,  it  forms  true 
ethers.  Hot  nitric  acid  oxidizes  it  to  cholesteric  acid,  C8H10O6,  which  is 
also  produced  by  the  oxidation  of  biliary  acids;  a  fact  which  indicates 
the  probable  existence  of  some  relation  between  the  methods  of  forma- 
tion of  cholesterin  and  of  the  biliary  acids  in  the  economy. 

Cholesterin  may  be  recognized  by  the  following  reactions:  1st,  moist- 
ened with  concentrated  nitric  acid  and  evaporated  to  dryness,  a  yellow 
residue  remains,  which  turns  brick-red  (not  bright  red,  as  in  the  case  of 
uric  acid)  on  the  addition  of  ammonium  hydrate;  2d,  it  is  colored  violet 
when  a  mixture  of  two  volumes  sulphuric  or  hydrochloric  acid,  and  one 
volume  ferric  chloride  solution  is  evaporated  upon  it;  3d,  when  ground 
up  with  sulphuric  acid  and  chloroform  added,  a  blue-red  or  violet  color  is 
produced,  which  passes  into  green  on  exposure  to  air. 


336  GENERAL   MEDICAJL   CHEMISTRY. 


Acids — SERIES  CnH2n_i0O3. 

Cinnamic  acid,  C8H7,COOH —  exists  in  syrax,  and  in  Peru  and 
Tolu  balsams;  it  is  also  formed  by  the  oxidation  of  cinnyl  alcohol;  by  the 
action  of  potassium  hydrate  an  essence  of  cinnamon;  and  by  heating 
together  acetyl  chloride  and  benzoyl  hydride  under  pressure. 

It  forms  prismatic  crystals';' &p.  gr.  1.J95;  fuses  at  137°;  boils  at  293°; 
quite  soluble  in  cold  water  and  ether. 

Cinnamic  aldehyde,  C8H7,COH — is  one  of  the  constituents  of 
essence  of  cinnamon.  It  is  a  colorless  oil;  denser  than  water;  turns  brown 
rapidly  on  exposure  to  air,  from  which  it  also  absorbs  oxygen  and  is 
converted  into  cinnamic  acid. 


SEVENTH  SERIES   OF  HYDROCARBONS. 


The  only  representative  of  this  series  at  present  known  is 
Naphthydrene  —  Naphthylene  hydride  —  C10H10  —  a  substance  having 
only  theoretical  interest,  obtained  by  heating  naphthalene  with  potassium, 
and  decomposing  the  product  with  water.  It  also  occurs  in  heavy  petro- 
leum. It  is  a  colorless  liquid;  boils  at  205°,  and  has  a  strong,  disagreeable 
odor. 

EIGHTH   SERIES   OF   IfYDROCARBONS. 


The  only  term  of  this  series  is 

Naphthalene,  C10H8  —  discovered  in  1820  in  coal-tar.  It  has  been 
formed  by  an  interesting  synthesis  which  indicates  its  constitution;  ben- 
zene and  ethylene,  when  heated  together,  unite  to  form,  first,  cinnamene 
(q.  v.\  and  afterward  naphthalene.  It  is  constituted  by  the  fusion  of  two 
benzol  groups  by  two  carbon-atoms,  thus: 

H        II 


k 


H-C       C       C-H 
H-C        o        C-H 


i 


It  is  obtained  in  considerable  quantities  from  coal-tar,  by  fractional 
distillation,  and  is  used  for  the  production  of  a  number  of  brilliant  dyes. 

It  crystallizes  in  large,  brilliant  plates;  has  a  burning  taste  and  a  faint 
aromatic  odor;  fuses  at  80°  and  boils  at  217°,  subliming,  however,  at  a 


ELEVENTH  SERIES  OF  HYDROCARBONS.         337 

temperature  much  below  its  boiling-point;  sp.  gr.  1.158  at  18°;  it  burns 
with  a  bright,  but  very  smoky  flame;  is  insoluble  in  cold  water,  very 
sparingly  soluble  in  boiling  water,  readily  soluble  in  alcohol,  ether,  and 
essences. 

Chlorine,  bromine,  nitric  acid,  and  concentrated  sulphuric  acid  attack 
it  to  form  substitution  compounds.  Alkalies  do  not  affect  it.  Nitric 
acid  after  a  time  oxidizes  it  to  phthalic  acid. 

Although  many  of  the  derivatives  of  naphthalene,  which  are  very  numer- 
ous, are  of  great  chemical  and  industrial  interest,  they  do  not  call  for  fur- 
ther mention  here. 


NINTH  SERIES  OF  HYDROCARBONS. 


Is  also  represented  by  a  single  hydrocarbon,  derived  from  naphthalene. 

Acenaphthalene,  C12H10  —  is  produced  synthetically  by  continuing 
the  heating  of  naphthalene  with  ethylene,  the  reaction  occurring  in  three 
steps. 

It  also  exists  in  coal-tar,  from  that  portion  of  which,  distilling  at  270° 
—  290°,  it  is  best  obtained. 

It  is  only  of  theoretical  interest. 


TENTH  SERIES  OP  HYDROCARBONS. 


Is  represented  by  two  terms:  Fluorene,  a  solid,  crystalline  body,  boil- 
ing at  305°,  obtained  from  coal-tar;  and  Stilbene,  obtained  by  the  action  of 
ammonium  sulphydrate  upon  an  alcoholic  solution  of  benzoic  aldelhyde. 


ELEVENTH  SERIES  OF  HYDROCARBONS. 


Anthracene,  C14H10,  is  a  substance  which,  although  of  but  little 
medical  interest,  has  assumed  considerable  importance  in  the  arts  and  in 
chemical  philosophy. 

It  exists  as  a  constituent  of  coal-tar,  and  is  obtained  by  expression 
from  the  substance  remaining  in  the  still  after  the  distillation  of  naphtha- 
lene, etc.  The  commercial  product,  thus  obtained  is  a  yellowish  mass 
containing  from  fifty  per  cent,  to  eighty  per  cent,  of  anthracene,  the  puri- 
fication of  which  is  a  matter  of  considerable  difficulty.  It  has  also  been 
obtained  synthetically. 

When  pure,  anthracene  crystallizes  in  rhombic  tables  having  a  bluish 
fluorescence;  fusible  at  210°  and  boiling  above  360°;  its  best  solvents  are 
benzene  and  carbon  disulphide,  in  which,  however,  it  is  only  sparingly 
soluble. 

Anthracene  forms  a  number  of  products  of  substitution;  the  only;  one- 
of  which  we  will  mention  is 
22 


338  GENERAL   MEDICAL   CHEMISTRY. 

Alizarin,  C14H8O4 — a  coloring  matter  now  prepared  on  a  large  scale 
from  anthracene,  formerly  only  obtained  from  madder,  and  very  exten- 
sively used  in  dyeing.  As  napthalene  is  formed  by  the  condensation  of 
two  molecules  of  benzene,  anthracene  is  constituted  by  the  condensation 
of  three;  the  constitution  of  anthracene  and  the  relation  of  alizarin  to  it 
are  shown  by  the  formulae: 

'""•• 


H_(j      0      0-H 

I       II       I 
H-C      0      C-H 


C      C 
H-O-C  C-O-H 


C-C 


Anthracene.  Alizarin. 


HIGHER  SERIES  OF  HYDROCARBONS. 

The  twelfth  series  is  not  at  present  represented.  Of  the  thirteenth 
series,  one  hydrocarbon,  pyrene,  C16H10,  is  known ;  and  one  of  the  fourteenth 
series,  chrysene,  C18H12,  both  obtained  from  coal-tar;  the  former  fusing  at 
142°,  the  latter  at  230°— 235C 


to 


CYANOGEN  COMPOUNDS. 

The  substances  which  we  have  considered  are  all  derivable,  more  or 
less  directly,  from  the  various  hydrocarbons,  and  may  be  considered,  upon 
the  theory  of  types,  to  be  formed  by  the  substitution  of  radicals  composed 
of  carbon  and  hydrogen,  carbon  and  oxygen,  or  carbon,  hydrogen  and 
oxygen,  for  atoms  of  hydrogen  of  the  three  typical  substances,  hydrogen, 
water,  and  ammonia.  There  are  a  number  of  very  important  substances 
which  are  typically  considered  as  containing  the  radical  (CN)',  which 
radical,  known  as  cyanogen,  possesses  the  same  power  of  passing  un- 
changed from  compound  to  compound,  as  do  methyl  and  ethyl,  like  which, 
also,  it  is  incapable  of  separate  existence.  The  substance  sometimes 
known  as  cyanogen  is  not  CN,  but 


Dicyanogen  (CN)a. 

This  body  is  prepared  by  heating  mercury  cyanide  in  a  small  retort 
and  collecting  the  gaseous  product  over  mercury. 

Dicyanogen  is  a  colorless  gas,  has  a  pronounced  odor  of  bitter 
almonds;  under  a  pressure  of  4  atm.  at  25°  it  is  liquefied;  sp.  gr.  1.8064  A.; 


HYDROGEN    CYANIDE.  339 

it  burns  in  air  with  a  purple  flame,  giving  off  nitrogen  and  carbon  dioxide. 
It  is  quite  soluble  in  water  ;  the  solution  on  exposure  to  air  turns 
brown;  with  water  alone,  or  with  water  and  ammonia,  dicyanogen  enters 
into  combinations  which  show  the  relations  existing  between  the  cyanogen 
compounds  and  others  previously  considered: 

(ON),      +      4H.O       =       0,04(NH4), 

Dicyanogen.  Water.  Ammonium  oxalate. 

(ON),       +       H20       =       CNOH       +       CNH 

Dicyanogen.  Water.  Cyanic  acid.  Hydrocyanic  acid. 

CNOH       +       H2O       =       NH3       +       CO2 

Cyanic  acid.  Water.  Ammonia.  Carbon  dioxide. 

CNOH     +     NH3     =     CON2H4 

Cyanic  acid.  Ammonia.  Urea. 

It  has  a  very  deleterious  action  upon  both  animal  and  vegetable  life, 
even  when  largely  diluted  with  air. 


Hydrogen  Cyanide. 

Cyanogen  hydride — Hydrocyanic  acid — Prussic  acid —   -^  j-  — exists 

ready  formed  in  the  juice  of  cassava,  and  is  formed  by  the  action  of  water 
upon  bitter  almonds,  cherry-laurel  leaves,  etc.  It  is  also  formed  in  a  great 
number  of  reactions:  by  the  passage  of  the  electric  discharge  through  a 
mixture  of  acetylene  and  nitrogen;  by  the  action  of  chloroform  on  am- 
monia; by  the  distillation  or  the  action  of  nitric  acid  upon  many  organic 
substances;  by  the  decomposition  of  cyanides. 

It  is  always  prepared  by  the  decomposition  of  a  cyanide,  although  the 
nature  of  the  cyanide  and  of  the  decomposing  agent  differ  in  the  process 
advised  by  different  authors,  and  according  as  the  product  is  required 
pure  or  in  dilute  solution.  Its  preparation  in  the  pure  form  is  an  opera- 
tion attended  with  the  most  serious  danger,  and  should  only  be  attempted 
by  those  well  trained  in  chemical  manipulation.  For  medical  uses  a  very 
dilute  acid  is  required;  the  acid.  dil.  hydrocyanicum  (U.  S.,  Br.)  con- 
tains, if  freshly  and  properly  prepared,  two  per  cent,  of  anhydrous  acid; 
that  of  the  French  Codex  is  much  stronger — ten  per  cent. 

The  pure  acid  is  a  colorless,  mobile  liquid,  has  a  penetrating  and 
characteristic  odor;  sp.  gr.  0.7058  at  7°;  crystallizes  at  — 15°;  boils  at 
26.5°;  is  rapidly  decomposed  by  exposure  to  light.  The  dilute  acid  of 
the  United  States  Pharmacopoeia  is  a  colorless  liquid,  having  the  odor  of 
the  acid;  faintly  acid,  the  reddened  litmus  returning  to  blue  on  exposure 
to  air;  sp.  gr.  0.997;  ten  grams  of  the  acid  should  be  accurately  neutral- 
ized by  1.27  grams  of  silver  nitrate.  The  dilute  acid  deteriorates  on  ex- 
posure to  light,  although  more  slowly  than  the  concentrated;  a  trace  of 
phosphoric  acid  added  to  the  solution  retards  the  decomposition. 

An  acid  of  the  medicinal  strength  may  be  obtained  extemporaneously 
from  argentic  cyanide  (q.  v.);  9.925  grams  of  the  pure,  dry,  salt  are  added 
to  a  mixture  of  8.3  grams  of  hydrochloric  acid  of  sp.  gr.  1.16  made  up  to 
98  c.c.,  with  distilled  water;  the  resulting  liquid,  after  agitation,  is  fil- 
tered from  the  precipitated  silver  chloride.  A  disadvantage  of  this  method 


340  GENERAL    MEDICAL    CHEMISTRY. 

is  that  while  an  excess  of  silver  nitrate  is  undesirable,  an  excess  of  hydro- 
chloric acid  rapidly  decomposes  hydrocyanic  acid,  with  formation  of  am- 
monium chloride  and  formic  acid;  the  neutralization  must  therefor  be  most 
accurate,  a  result  not  readily  attained  in  practice.  The  acid  known  as 
Scheelds  contains  five  per  cent,  of  true  acid. 

Most  powerful  acids  decompose  hydrocyanic  acid  quickly;  the  alka- 
lies enter  into  double  decomposition  with  it  to  form  cyanides;  chlorine 
and  bromine  decompose  it,  With  formation  of  cyanogen  chloride  and  bro- 
mide; nascent  hydrogen  converts  it  into  rnethylamine. 

The  presence  of  hydrocyanic  acid  or  of  a  soluble  cyanide  is  recognized 
by  the  following  characters:  1st,  with  silver  nitrate  a  dense,  white  precip- 
itate is  formed;  the  precipitate  is  not  redissolved  on  the  addition  to  the 
liquid  of  a  small  quantity  of  nitric  acid,  but  is  dissolved  if  separated  and 
heated  with  concentrated  nitric  acid;  it  is  but  sparingly  soluble  in  am- 
monia; freely  soluble  in  solutions  of  alkaline  cyanides  or  hyposulphites. 
2d,  when  treated  with  a  solution  of  ammonium  sulphydrate,  and  a  solu- 
tion of  ferric  chloride  added,  a  blood-red  color  is  produced.  3d,  on  the 
addition  of  potassium  hydrate,  and  subsequently  of  a  mixture  of  ferrous 
and  ferric  sulphates,  a  greenish  precipitate  is  formed,  which  is  partly  re- 
dissolved  by  hydrochloric  acid,  leaving  a  deep  blue  color.  4th,  a  dilute 
solution  of  picric  acid  produces  a  blood-red  color  when  heated  with  a  cy- 
anide and  subsequently  cooled. 

Toxicology. — Hydrocyanic  acid  is  a  violent  poison,  whether  it  be  in- 
haled as  vapor  or  swallowed,  either  in  the  form  of  dilute  acid,  of  soluble 
cyanide,  or  of  the  pharmaceutical  preparations  containing  it,  such  as  oil 
of  bitter  almonds  and  cherry-laurel  water,  its  action  being  more  rapid 
when  taken  by  inhalation  or  in  aqueous  solution  than  in  other  forms. 
When  the  medicinal  acid  is  taken  in  poisonous  dose,  its  lethal  effect  may 
seem  to  be  produced  instantaneously;  nevertheless,  several  respiratory 
efforts  usually  are  made  after  the  victim  seems  to  be  dead,  and  instances 
are  not  wanting  in  which  there  was  time  for  considerable  voluntary  motion 
between  the  time  of  the  ingestion  of  the  poison  and  unconsciousness.  In 
the  great  majority  of  cases  the  patient  is  either  dead  or  fully  under  the  in- 
fluence of  the  poison  on  the  arrival  of  the  physician,  who  should,  however, 
not  neglect  to  apply  the  proper  remedies  if  the  faintest  spark  of  life  remain. 
Chemical  antidotes  are,  owing  to  the  rapidity  of  action  of  the  poison,  of 
110  avail,  although  possibly  chlorine,  recommended  as  an  antidote  by  many, 
may  have  a  chemical  action  on  that  portion  of  the  acid  already  absorbed. 
The  treatment  indicated  is  directed  to  the  maintenance  of  respiration; 
cold  douche,  galvanism,  artificial  respiration  until  elimination  has  removed 
the  poison.  If  the  patient  survive  an  hour  after  taking  the  poison,  the 
prognosis  becomes  very  favorable;  in  the  first  stages  it  is  exceedingly 
unfavorable,  unless  the  quantity  taken  has  been  very  small. 

In  cases  of  death  from  hydrocyanic  acid  a  marked  odor  of  the  poison 
is  almost  always  observed  in  the  apartment  and  upon  opening  the  body, 
even  several  days  after  death.  In  cases  of  suicide  or  accident,  the  vessel 
from  which  the  poison  has  been  taken  will  usually  be  found  in  close 
proximity  to  the  body,  although  the  absence  of  such  vessel  is  not  proof 
that  the  case  is  one  of  homicide. 

The  presence  of  hydrocyanic  acid  may  be  readily  detected  in  the  body 
after  death,  and,  notwithstanding  the  volatility  and  instability  of  the 
poison,  its  presence  has  been  detected  two  months  after  death,  although 
the  chances  of  separating  jt  are  certainly  the  better  the  sooner  after 
death  the  analysis  is  made.  The  search  for  hydrocyanic  acid  is  combined 


METALLOCYANIDES.  341 

with  that  for  phosphorus  (see  p.  109);  the  part  of  the  distillate  contain- 
ing the  more  volatile  products  is  examined  by  the  tests  given  above;  it 
is  best,  when  the  presence  of  free  hydrocyanic  acid  is  suspected,  to  dis- 
til at  first  without  acidulating;  in  such  cases  the  stomach  should  never 
be  opened  until  immediately  before  the  analysis. 


Cyanic  Acid. 

Cyanogen  hydrate,     TT  /O — does  not  exist  in  nature;  it  is  obtained 

by  calcining  the  cyanides  in  presence  of  an  oxidizing  agent;  or  by  the 
action  of  dicyanogen  upon  solutions  of  the  alkalies  or  alkaline  carbo- 
nates; the  best  method  of  obtaining  it  is  by  the  distillation  of  cyanuric 
acid. 

It  is  a  colorless  liquid;  has  a  strong  odor,  resembling  that  of  formic 
acid;  its  vapor  is  irritating  to  the  eyes,  and  it  produces  vesication  when 
applied  to  the  skin;  it  is  soluble  in  water.  When  free  it  is  readily 
changed  by  exposure  to  air  into  cyamelide.  The  acid  itself  is  of  little 
interest;  some  of  its  salts  and  ethers,  however,  are  of  industrial  im- 
portance. 

Sulphocyanic  Acid. 

CNV 
Cyanogen  sulphydrate,      TT  /S — bears  the  same  relation  to  cyanic 

acid  that  carbon  disulphide  does  to  carbon  dioxide.  It  is  obtained  by 
the  decomposition  of  its  salts,  which  are  obtained  by  boiling  a  solution  of 
the  cyanide  with  sulphur,  by  the  action  of  dicyanogen  upon  the  metallic 
sulphide,  and  in  several  other  ways. 

The  free  acid  is  a  colorless  liquid;  crystallizes  at  — 12.5°;  boils  at 
102.5°;  acid  in  reaction;  sp.  gr.  1.040  at  17°.  The  prominent  reaction 
of  the  acid  and  of  its  salts  is  the  production  of  a  deep  red  color  with  the 
ferric  salts;  the  color  being  discharged  by  solution  of  mercuric  chloride, 
but  not  by  hydrochloric  acid. 

Sulphocyanic  acid  exists  in  human  saliva  in  combination,  probably, 
with  sodium.  The  free  acid  is  actively  poisonous  and  its  salts  were  for- 
merly supposed  to  be  so  also;  it  is  probable,  however,  that  much  of  the 
deleterious  action  of  the  potassium  salt — that  usually  experimented  with — 
is  due  as  much  to  the  metal  as  to  the  acid. 


Metallocyanides. 

The  radical  cyanogen,  besides  combining  with  metallic  elements  to 
form  true  cyanides,  in  which  the  radical  (CN)  enters  as.  a  univalent  atom, 
is  capable  of  combining  with  certain  metals;  notably  those  of  the  iron 
and  platinum  groups,  to  form  still  more  complex  radicals,  which,  combin- 
ing with  hydrogen,  form  acids,  and  with  basic  elements  form  salts  in 
which  the  analytical  reactions  of  the  metallic  element  entering  into  the 
radical,  are  completely  masked.  Of  these  metallocyanides  the  best  known 
are  those  in  which  iron  enters  into  the  radical.  As  iron  is  capable  of 
forming  two  series  of  compounds,  in  one  of  which  the  single  atom  Fe" 
enters  in  its  divalent  capacity,  and  in  the  other  of  which  the  hexavalent 


342  GENERAL    MEDICAL    CHEMISTRY. 

double  atom  (Fe0)vl  is  contained;  so,  uniting  with  cyanogen,  iron  forms 
two  ferrocyanogen  radicals:  [(CN)'6Fe"]iv,  ferrocyanogen,  and  [(CN)'12 
(Fe2)vi]vi,  ferricyanogen,  each  of  which  unites  with  hydrogen  to  form  an 
acid,  corresponding  to  which  are  numerous  salts:  (C6N6Fe)H4,  hydrofer- 
rocyanic  acid,  tetrabasic;  and  (C12N12Fe2)H6,  hydroferricyanic  acid,  hex- 
abasic  (see  potassium  and  iron  salts). 


COMPOUNDS   OF   UNKNOWN   CONSTITUTION. 

GLUCOSIDES. 

Under  this  head  are  classed  a  number  of  substances,  some  of  them  im- 
portant medicinal  agents,  which  are  the  products  of  vegetable  or  animal 
nature;  their  characteristic  property  is  that,  under  the  influence  of  a 
dilute  mineral  acid,  they  yield  glucose,  phloroglucine  or  rnannite,  together 
with  some  other  substance.  Under  the  supposition  that  glucose  and  its 
congeners  are  alcohols,  it  is  quite  probable  that  the  glucosides  are  their 
corresponding  ethers. 

Some  of  the  more  important  glucosides  are  treated  of  below  in  alpha- 
betical order: 

Amygdalin,  C00H07NOn,  exists  in  cherry-laurel  and  in  bitter  almonds, 
but  not  in  sweet  almonds.  Its  characteristic  reaction  is  that,  in  the  pres- 
ence of  emulsin,  which  exists  in  sweet  as  well  as  in  bitter  almonds, 
and  of  water,  it  is  decomposed  into  glucose,  benzoic  aldehyde,  and  hydro- 
cyanic acid. 

The  same  reaction  is  brought  about  by  boiling  with  dilute  sulphuric 
or  hydrochloric  acids.  Bitter  almonds  contain  about  two  per  cent,  of 
amygdalin. 

Api'in,  C24H280]3,  is  a  glucoside  obtained  from  parsley.  Dilute  acids 
decompose  it  into  a  white,  flocculent  substance  of  unknown  composition, 
and  a  non-fermentable,  uncrystallizable  sugar. 

Arbutin,  C12H16O7(?) — a  glucoside  supposed  to  be  the  active  princi- 
ple of  uva  ursi,  is  a  bitter,  crystalline  substance,  very  soluble  in  water, 
decomposed  by  emulsin  or  by  dilute  acids  into  glucose  arid  hydroquinon. 

Carminic  acid,  C17H18010,  is  the  red  coloring  matter  of  cochenil; 
dilute  sulphuric  acid  decomposes  it  into  a  non-fermentable  sugar  and  a 
new  red  pigment,  insoluble  in  ether,  but  soluble  in  alcohol. 

Cathartic  acid — a  bitter,  uncrystallizable  glucoside,  obtained  from 
senna. 

Chitin  is  an  animal  product,  and  forms  the  organic  basis  of  the 
tissues  of  insects,  spiders,  and  crustaceans.  It  withstands  the  action  of 
reagents  well,  but,  when  boiled  with  dilute  sulphuric  acid,  yields  ammo- 
nia, a  fermentable  sugar,  and  a  substance  which  appears  to  be  lactamide. 

Colocynthin — a  very  bitter  and  actively  purgative  glucoside,  ob- 
tained from  colocynth,  soluble  in  water  and  alcohol;  decomposed  by  dilute 
acids  into  a  resin,  colocynthein,  and  glucose. 

Crocin — a  yellowish  red  glucoside  obtained  from  saffron;  soluble  in 
alcohol;  decomposed  into  crocetin  and  a  sugar  resembling,  but  not  identi- 
cal with,  glucose. 

Digitalin. — The  substance  known  until  recently  as  digitalin  was  an 
uncrystallizable  material,  soluble  in  water,  obtained  from  digitalis,  whose 
medicinal  properties  it  possessed  to  a  high  degree.  More  recent  re- 
searches have,  however,  shown  that  this  substance,  although  very  active, 


GLUCOSIDES.  343 

does  not  contain  all  the  active  principles  of  the  plant,  which  contains  the 
true  glucoside  as  a  crystalline  substance,  insoluble  in  water,  but  soluble  in 
alcohol.  By  a  complicated  system  of  extraction  by  water  and  by  alcohol, 
and  decolorization  and  purification  of  the  extracts,  Nativelle  has  obtained 
from  all  parts  of  the  plant,  except  the  seeds,  1st,  a  gummy,  uncrystallizable, 
white  substance,  soluble  in  water,  sparingly  soluble  in  alcohol;  very  bitter, 
acrid,  and  irritating,  which  he  calls  amorphous  digitaleine  ;  2d,  the  true 
glucoside,  insoluble  digitalin,  which  crystallizes  in  fine  needles,  almost  in- 
soluble in  water,  readily  soluble  in  alcohol;  intensely  and  persistently 
bitter,  and  actively  poisonous.  Sulphuric  acid  dissolves  it  with  a  green- 
ish brown  color,  changing  to  red  under  the  influence  of  bromine  vapor, 
and  to  emerald  green  on  subsequent  dilution  with  water.  Hydrochloric 
acid  of  20°  strength  dissolves  it,  the  solution  assuming  in  a  few  moments 
a  fine  green  color.  When  suspended  in  water  and  treated  with  sulphuric 
acid  it  is  entirely  decomposed,  with  production  of  glucose  and  a  peculiar 
substance,  digitaliretin,  015H2505.  Digitalis  also  contains  a  white,  insipid 
crystalline  substance,  insoluble  in  water — digitalose,  and  a  crystallizable 
acid — digitalic  acid,  very  soluble  in  water  and  in  alcohol;  very  prone  to 
decomposition  when  exposed  to  light;  acid  in  taste  and  in  reaction. 

For  the  detection  of  digitalin  in  cases  of  poisoning,  see  p.  348. 

Glycyrrhizin — a  non-crystallizable,  yellowish,  pulverulent  principle, 
obtained  from  liquorice;  soluble  with  difficulty  in  cold  water,  soluble  in 
hot  water,  alcohol,  and  ether;  bitter-sweet  in  taste.  By  long  boiling  with 
dilute  acids  it  is  decomposed  into  glucose  and  glycyrrhetin,  C18H2604. 

Jalapin,  C34H50O16,  is  the  active  principle  of  scammony,  and  exists 
also  to  a  limited  extent  in  jalap  (see  below).  It  is  an  insipid,  colorless, 
amorphous  substance,  whicli  is  decomposed  by  dilute  acids  into  glucose 
and  jalapinol.  The  active  ingredient  of  jalap  is  not,  as  the  name  would 
imply,  jalapine,  but  a  resinous  substance  called  convolvulin,  which  is  in- 
soluble in  ether,  odorless,  and  insipid.  It  is  not  attacked  by  dilute  sul- 
phuric acid,  although  the  concentrated  acid  dissolves  it  with  a  carmine- 
red  color,  slowly  turning  to  brown;  in  alcoholic  solution  it  is  decomposed 
by  gaseous  hydrochloric  acid  into  glucose  and  convolvulinic  acid.  It  is 
an  active  purgative  agent. 

Phlorizin,  C21H24O10,  is  a  glucoside  obtained  from  the  bark  of  apple-, 
plum-,  pear-trees,  etc.;  it  crystallizes  is  silky  needles;  sparingly  solub  e  in 
cold  water,  very  soluble  in  hot  water  and  in  alcohol.  Is  colored  yellow,  then 
brown,  by  sulphuric  acid;  dilute  acids  decompose  it  into  glucose  and 
phloretin,  C16H14O5. 

Quercitrin,  or  quercitric  acid — obtained  from  black-oak  bark;  crys- 
tallizes in  rectangular  or  rhombic  plates;  neutral;  odorless;  bitter;  almost 
insoluble  in  cold  water;  soluble  in  hot  water  and  in  alcohol;  readily  soluble 
in  alkaline  solutions,  with  a  greenish  yellow  color,  turning  to  brown  by 
oxidation  on  exposure  to  air.  Dilute  mineral  acids  decompose  it  into  iso- 
dulcite,  C6H14O6,  and  quercetin,  C27II18O12. 

Quinovin,  or  quinovatic  acid,  a  bitter  principle,  possessed  of  acid 
functions,  obtained  from  the  false  bark  known  as  cinchona  nova;  it  is  a 
glucoside,  being  decomposed  by  dilute  acids  into  a  sugar  resembling 
mannitan  and  qicinovic  acid. 

Salicin,  C13H18O7 — one  of  the  best  known  of  the  glucosides;  derives 
its  name  from  its  chief  source,  the  bark  of  the  willow  (salix).  It  is  a 
white,  crystalline  substance;  insoluble  in  ether,  soluble  in  water  and  in 
alcohol;  fuses  at  120°,  and  is  decomposed  at  a  temperature  above  200°;  it 
is  very  bitter;  its  solutions  are  dextrogyrous,  [a]D^55.8°.  Dilute  acids 


344  GENERAL    MEDICAL    CHEMISTRY. 

decompose  it  into  glucose  and  saligenin  (q.  v.}.  Concentrated  sulphuric 
acid  colors  it  red,  the  color  being  discharged  on  the  addition  of  water. 
When  taken  into  the  economy  it  is  converted  into  salicylic  aldehyde  and 
acid,  which  are  eliminated  in  the  urine. 

Santonin — Santonic  acid — C]6H18O3 — Santoninum  (U.  S.,  Br.) — a 
glucoside  having  distinct  acid  properties;  obtained  from  various  species 
of  Artemisia  (Levant  worm-seed).  It  crystallizes  in  colorless,  rectangular 
prisms,  which  turn  yellow  on  exposure  iff  light;  odorless  and  tasteless;  in- 
soluble in  cold  water,  sparingly  soluble  in  hot  water,  alcohol,  and  ether; 
its  solutions  are  faintly  acid  in  reaction.  Sulphuric  acid,  aided  by  heat, 
decomposes  it  into  glucose  and  a  yellowish,  odorless,  tasteless  resinoid,  in- 
soluble in  water,  soluble  in  alcohol,  called  santoniretin.  Santonin,  in  so- 
lution, gives  a  chamois-colored  precipitate  with  the  ferric  salts,  and  a 
white  precipitate  with  silver,  zinc,  and  mercurous  salts;  no  precipitate 
with  mercuric  salts. 

Patients  taking  santonin  pass  urine  having  the  appearance  of  that 
containing  bile,  which,  when  treated  with  potash,  turns  cherry-red  or 
crimson,  the  color  being  discharged  by  an  acid,  and  regenerated  on  neu- 
tralization. 

Solanin — a  glucoside,  having  basic  properties,  existing  in  different 
plants  of  the  genus  Solanum.  It  crystallizes  in  fine,  white,  silky  needles; 
having  an  acrid,  bitter  taste;  insoluble  in  water,  and  but  sparingly  soluble 
in  ether  and  in  alcohol.  By  the  action  of  hot  dilute  acids  it  is  decom- 
posed into  glucose  and  a  basic  substance,  solanidine;  when  not  heated, 
solanin  combines  with  acids  to  form  uncrystallizable  salts.  Cold,  con- 
centrated sulphuric  acid  colors  it  orange-yellow,  and  finally  forms  with  it 
a  brown  solution ;  nitric  acid  dissolves  it,  the  solution  being  at  first  color- 
less, afterward  rose-pink. 

Tannin — Tannic  acid — C14H10O9. — Quite  a  number  of  different  sub- 
stances of  vegetable  origin,  principally  derived  from  barks,  leaves,  and 
seeds.  They  are  amorphous,  soluble  in  water,  astringent,  capable  of 
precipitating  albumen  and  of  forming  imputrescible  compounds  with  the 
gelatinoids.  They  are,  with  one  possible  exception,  glucosides.  The 
principal  varieties  are  the  following: 

Gallo-tannic  acid — Acidum  tannicum  (U.  S.,  Br.) — is  the  best  known 
of  the  tannins,  and  is  obtained  from  nut-galls,  galla  (U.  S.,  Br.),  which 
are  excrescences  produced  upon  oak-trees  by  the  puncture  of  minute  in- 
sects. It  appears  as  a  yellowish,  amorphous,  odorless,  friable  mass;  has 
an  astringent  taste;  very  soluble  in  water,  less  so  in  alcohol,  almost  insol- 
uble in  ether;  its  solutions  are  acid  in  reaction,  and  on  contact  with  ani- 
mal tissues  give  up  the  dissolved  tannin,  which  becomes  fixed  by  the 
tissue  to  form  a  tough,  insoluble,  and  non-putrescible  material  (leather). 

Solutions  of  gallo-tannic  acid  yield  insoluble  precipitates  with  sulphuric, 
hydrochloric,  phosphoric,  and  arsenic  acids,  sodium  chloride,  potassium 
acetate,  gelatin,  and  ammonium  chloride.  It  also  precipitates  solutions 
of  most  of  the  metallic  salts,  in  many  instances  effecting  a  reduction  and 
separation  of  the  metallic  element.  The  tannates  of  the  alkaline  metals 
are  soluble,  and  become  colored  on  exposure  to  air;  almost  all  other  tan- 
nates  are  insoluble,  including  those  of  the  vegetable  alkaloids. 

A  freshly  prepared  solution  of  pure  gallo-tannic  acid  gives  a  dark  blue 
precipitate  with  ferric  salts,  but  not  with  ferrous  salts.  If,  however,  the 
solution  have  been  exposed  to  the  air,  it  is  altered  by  oxidation,  and  gives, 
with  ferrous  salts,  a  black  color,  in  whose  production  gallic  acid  probably 
plays  an  important  part,  which  is  the  coloring  material  of  ordinary  writing- 


GLUCOSIDES.  345 

ink.  A  good  ink  is  made  by  boiling  six  parts  of  crushed  nut-galls  in 
forty-five  parts  (by  weight)  of  water  for  three  hours,  replacing  the  water 
as  it  evaporates,  cooling  arid  filtering;  a  solution  containing  2.5  parts  of 
gum  arabic  dissolved  in  a  small  quantity  of  water  and  strained,  and,  finally, 
a  concentrated  solution  of  2.5  parts  of  ferrous  sulphate,  are  added;  the 
mixture  is  exposed  to  the  air  until  it  has  assumed  the  proper  tint  (two  to 
three  weeks),  decanted,  and  bottled.  The  color  of  this  ink  is  discharged 
by  oxalic  and  sulphuric  acids.  Removals  of  writing  in  iron  ink  by  acids 
may  be  detected  by  first  moistening  with  pure  water,  and  testing  by  lit- 
mus paper;  the  reaction  will  be  acid,  unless  the  acid  have  been  neutralized; 
the  surface  is  then  pencilled  with  a  dilute  solution  of  ammonia,  and  after- 
ward with  a  solution  of  nut-galls,  when  the  writing  will  become  more  or 
less  plainly  visible. 

Other  characters  of  gallo-tannic  acid  are  the  formation  of  precipitates 
with  solutions  of  albuminoids,  gelatin,  alkaloids,  and  tartar  emetic.  Its 
watery  solution  remains  unaltered  when  protected  from  air,  but  by  expo- 
sure it  becomes  colored  and  mouldy,  ferments,  and  is  converted  into  gallic 
acid;  the  same  changes  are  caused  by  dilute  acids  and  in  the  economy 
when  gallo-tannic  acid  is  ingested. 

Although  formerly  considered  as  a  glucoside,  and,  in  all  probability, 
existing  as  such  in  vegetable  nature,  recent  researches  have  shown  gallo- 
tannic  acid  to  be,  not  a  glucoside,  but  digallic  acid. 

Caffetannic  acid  exists  in  saline  combination  in  coffee  and  in  Paraguay 
tea.  It  colors  the  ferric  salts  green,  and  does  not  affect  the  ferrous  salts, 
except  in  the  presence  of  ammonia;  it  precipitates  the  salts  of  quinine 
and  of  cinchonine,  but  does  not  precipitate  tartar  emetic  or  gelatin.  It 
is  a  glucoside,  being  decomposed  by  suitable  means  into  caffeic  acid  and 
mannitan. 

Cachoutannic  acid,  obtained  from  catechu,  is  soluble  in  water,  alco- 
hol, and  ether.  Its  solutions  precipitate  gelatin,  but  not  tartar  emetic; 
they  color  the  ferric  salts  grayish  green. 

Morintannic  acid — Maclurin — a  yellow,  crystalline  substance,  ob- 
tained from  fustic;  more  soluble  in  alcohol  than  in  water.  Its  solutions 
precipitate  green  with  ferroso-ferric  solutions;  yellow  with  lead  acetate; 
brown  with  tartar  emetic;  yellowish  brown  with  cupric  sulphate.  It  is 
decomposable  into  phloroglucin  and  protocatechuic  acid. 

Quercitannic  acid  is  the  active  tanning  principle  of  oak-bark;  it  dif- 
fers from  gallo-tannic  acid  in  not  being  capable  of  conversion  into  gallic 
acid,  and  in  not  furnishing  pyrogallol  on  dry  distillation.  It  forms  a  vio- 
let-black precipitate  with  ferric  salts.  The  tannin  existing  in  black  tea 
seems  to  be  quercitannic  acid. 

Quinotannic  acid,  a  tannin  existing  in  cinchona  barks,  probably  in 
combination  with  the  alkaloids.  It  is  a  light  yellow  substance;  soluble 
in  water,  alcohol,  and  ether;  its  taste  is  astringent,  but  not  bitter.  Di- 
lute sulphuric  acid  decomposes  it,  at  a  boiling  temperature,  into  glucose 
and  a  red  substance — quinova  red. 

The  tannin  existing  in  wines,  especially  in  new  red  wines,  appears  to 
be  a  mixture  of  at  least  two  tannins,  one  derived  from  the  seeds  and 
stems  of  the  grape  (none  exists  in  the  juice),  and  the  other  from  the 
wood  of  the  cask;  it  has  the  valuable  property  of  forming  an  insoluble 
compound  with  albumen,  and  thus  removes  and  prevents  further  change 
of  the  albuminoids. 


346  GENERAL    MEDICAL    CHEMISTRY. 


NATURAL  ALKALOIDS. 

Under  this  head  are  classed  a  number  of  substances  of  great  interest 
to  the  physician.  They  exist  for  the  most  part  in  vegetable  nature,  com- 
bined with  acids,  for  which  reason  they  are  sometimes  called  vegetable 
bases,  or  vegetable  alkalies;  the  comparatively  recent  discovery,  however, 
of  substances  possessing  all  the  characteristics  of  alkaloids  in  materials  of 
animal  origin,  renders  these  terms  inapplicable. 

The  alkaloids,  as  the  name  implies,  bear  some  resemblance  to  the  al- 
kalies; they  are  alkaline  in  reaction,  and  combine  with  acids  to  form  salts 
in  the  same  way  as  does  ammonia;  there  is  good  reason  for  believing, 
also,  that  these  salts,  as  those  of  the  amines  (q.  v.),  are  compounds  of  radi- 
cals bearing  the  same  relation  to  the  alkaloid  itself  that  ammonium  bears 
to  ammonia: 

2NH3   +   S04H2  =  S04(NH4)2 

Ammonia.  Sulphuric  Ammonium 

acid.  sulphate. 

2C17H,,NO,  +  SO.H,  =  SO.tC.^.NO.), 

Morphia.  Sulphuric  acid.  Morphonium  sulphate. 

They  may  be  divided  into  two  principal  groups;  those  of  the  first  are 
liquid  and  volatile,  and  are  composed  of  carbon,  hydrogen,  and  nitrogen; 
the  synthesis  of  one  of  their  number,  effected  by  Schiff,  leaves  no  doubt 
that  they  are  true  amines.  The  members  of  the  second  group  are  solid, 
volatilizable  with  difficulty,  if  at  all,  and  are  composed  of  carbon,  hydro- 
gen, nitrogen,  and  oxygen.  Although,  in  spite  of  much  patient  research, 
no  chemist  has  hitherto  succeeded  in  effecting  the  synthesis  of  an  oxygen- 
ated alkaloid,  their  compounds  and  the  products  of  their  decomposition 
lead  us  to  believe  it  highly  probable  that  they  will  be  found  to  be  amides. 
The  solid  alkaloids  are  all  colorless,  bitter,  insoluble,  or  sparingly  soluble 
in  water,  and  most  of  them  crystallize  readily  and  perfectly. 

A  knowledge  of  certain  physical  and  chemical  properties  possessed  in 
varying  degrees  by  the  alkaloids  in  common,  is  of  great  value  in  phar- 
maceutical and  toxicological  chemistry. 

Solubility.  —  As  a  rule  the  alkaloids  are  insoluble  in  water,  or  nearly 
so,  more  soluble  in  alcohol,  chloroform,  petroleum  ether,  and  benzene; 
the  solubility  of  the  salts  of  the  alkaloids  differs  in  a  remarkable  way  from 
that  of  the  alkaloids  themselves,  for,  while  both  are  soluble  in  alcohol,  the 
salts  are,  for  the  most  part,  soluble  in  water  and  the  alkaloids  are  not;  on 
the  other  hand,  the  alkaloids  are  soluble  in  petroleum  ether,  benzene, 
ether,  chloroform,  and  amyl  alcohol,  in  which  menstrua  their  salts  are 
either  insoluble  or  very  sparingly  soluble.  It  is  upon  these  differences  of 
solubility  that  the  methods  for  separating  alkaloids,  etc.,  from  animal 
tissues  are  based  (see  below). 

Rotary  power. — All  the  natural  alkaloids  exert  a  rotary  action  upon 
polarized  light,  and  all,  with  the  exception  of  cinchonine  and  quinidine, 
are  lasvogyrous.  As  a  rule,  their  rotary  action  is  diminished  by  combina- 
tion with  an  acid,  in  the  absence  of  an  excess  of  acid;  with  quinine,  how- 
ever, the  reverse  is  the  case;  narcotine,  when  free,  is  laevogyrous,  but  in  its 
salts  is  dextrogyrous. 


NATUKAL    ALKALOIDS.  347 

The  rotary  powers  of  the  principal  alkaloids  are  the  following: 

Quinine [«]  =  -126.7°    j  Codeine [a]  =  -118.2° 

"'  Narceine [a]  6.7° 

Strychnine [a]     —132.07° 

Brucine [a]     —  61.27° 

Nicotine [a]     —  93.5° 


Quinidine    [a]  +250.75 

Cinchonine [a]  + 190.4° 

Cinchonidine [<fj  — 144.61° 

Morphine [a]  -  88.04° 

Narcotine [a]  — 103.5° 


General  reactions. — Potash,  soda,  ammonia,  lime,  baryta,  and  mag- 
nesia precipitate  the  alkaloids  from  solutions  of  their  salts. 

Quite  a  number  of  reagents  have  been  suggested  by  various  authors, 
which  give  with  solutions  of  the  salts  of  all  the  alkaloids,  even  when  very 
dilute,  characteristic  precipitates.  The  principal  of  these  reagents  are: 

Phosphomolybdic  acid. — The  reagent  is  prepared  as  follows:  am- 
monium molybdate  is  dissolved  in  water;  the  solution  filtered,  and  a 
quantity  of  crystallized  hydrodisodic  phosphate,  one-fifth  in  weight  of  the 
molybdate  used,  is  added,  and  then  nitric  acid  to  strong  acid  reaction; 
the  mixture  is  warmed  and  set  aside  for  a  day  or  more.  The  yellow  pre- 
cipitate is  collected  on  a  filter,  washed  with  water,  acidulated  with  nitric 
acid,  and,  while  still  moist,  transferred  to  a  porcelain  capsule,  to  which 
the  liquid  obtained  by  exhausting  the  remainder  on  the  filter  with  am- 
monium hydrate  is  added.  The  fluid  so  obtained  is  warmed  and  gradu- 
ally treated  with  pulverized  sodium  carbonate  until  a  colorless  solution  is 
obtained;  this  is  evaporated  to  dryness,  a  few  crystals  of  sodium  nitrate 
are  added  to  the  residue,  and  the  whole  gradually  heated  to  quiet  fusion, 
and  until  the  ammonia  has  been  expelled.  After  cooling,  the  residue  is 
dissolved  in  warm  water  in  the  proportion  of  one  to  ten,  acidulated  with 
nitric  acid,  and  decanted. 

To  use  the  reagent,  a  drop  of  the  suspected  solution  is  placed  upon  a 
glass  plate  with  a  black  background,  and  near  it  a  drop  of  the  reagent; 
the  two  drops  are  then  made  to  mix  slowly  by  a  pointed  glass  rod.  In 
the  presence  of  even  a  minute  trace  of  an  alkaloid  (or  of  certain  other 
substances)  a  precipitate  is  formed,  which  is  bright  yellow  and  flocculent 
with  aniline,  morphine,  veratrine,  aconitine,  emetine,  atropine,  hyoscya- 
mine;  bright  yellow  and  voluminous  with  theine,  theobromine,  conii'ne, 
nicotine;  brownish  yellow  with  narcotine,  codeine,  piperine;  yellowish 
white  with  quinine,  cinchonine,  strychnine;  yolk-yellow  with  brucine. 

The  value  of  this  reagent  is  not  in  its  capacity  to  differentiate  between 
the  various  alkaloids,  but  in  its  indication  of  the  2wobable  presence  or  cer- 
tain absence  of  some  alkaloid  in  appreciable  quantity. 

Potassium  iodhydrargyrate,  obtained  by  dissolving  13.546  grams  of 
mercuric  chloride  and  49.8  grains  of  potassium  iodide  in  a  litre  of  water. 
A  very  sensitive  reagent  when  applied  to  alkaloidal  solutions  which  are 
either  acid,  neutral,  or  very  faintly  alkaline  in  reaction. 

The  solution,  made  of  the  above  strength,  may  be  used  for  quantitative 
determinations.  The  reagent  is  added  from  a  burette  to  the  solution  of 
alkaloid  until  a  drop,  filtered  from  the  solution  which  is  being  tested,  and 
placed  upon  a  black  surface,  gives  no  precipitate  with  a  drop  of  the  re- 
agent. Each  c.c.  of  reagent  used  indicates  the  presence  in  the  volume 
of  liquid  tested  of  the  following  quantities  of  alkaloids,  in  grams: 


Aconitine 0.0267  |  Brucine 0.0233 

Atropine 0 . 0145  I  Veratrine 0.0269 

Narcotine 0 . 0213   Morphine 0. 0200 

Strychnine 0.0167 1  Coniine 0.00416 


Nicotine 0.00405 

Quinine 0.0108 

Cinchonine 0.0102 

Quinidine 0.0120 


348  GENERAL    MEDICAL    CHEMISTRY. 

Of  course,  the  process  can  be  used  only  in  a  solution  containing  a  single 
alkaloid. 

•Separation  of  alkaloids  from  organic  mixtures  and  from  each  other. — 
One  of  the  most  difficult  of  the  toxicologist's  tasks  is  the  separation  from 
a  mixture  of  organic  material  (contents  of  stomach,  viscera)  of  an  alkaloid 
in  such  a  state  of  purity  as  to  render  its  identification  perfect.  The  diffi- 
culty is  the  greater  if  the  amount  present  be  small,  as  is  usually  the  case; 
and  if  the  search  be  not  confined  to  a  single  alkaloid,  as  frequently  occurs. 
Some  of  these  substances,  as  strychnine,  are  detectable  with  much  greater 
facility  and  certainty  than  others. 

Of  the  processes  hitherto  suggested,  the  best  is  that  of  Dragendorff 
(Gerichtl.  Chem.  Ermittel.  der  Gifte,  p.  141,  1876;,  it  having  been 
devised  for  the  detection  of  any  alkaloid  or  poisonous  organic  principle 
present  in  the  substances  examined,  is  very  exhaustive,  and  well  adapted 
to  cases  frequently  arising  in  chemico-legal  practice;  but,  on  the  other 
hand,  is  too  intricate  to  be  serviceable  to  the  general  practitioner. 

An  abridgment  of  this  process  may  be  of  use  to  detect  the  presence 
of  the  more  commonly  used  alkaloids  in  a  mixture  of  organic  material. 
The  physician  should,  however,  bear  in  mind  that,  in  cases  liable  to  give 
rise  to  legal  proceedings,  these  may  become  seriously  complicated  by  the 
analysis  of  any  parts  of  the  body,  dejecta,  or  suspected  articles  of  food, 
etc.,  by  any  process  open  to  attack  by  the  most  searching  cross-ex- 
amination. 

The  substances  to  be  examined  are  reduced  to  a  fine  state  of  sub- 
division, and  are  digested  for  an  hour  or  more  in  water  acidulated  with 
sulphuric  acid,  at  a  temperature  of  40°  to  50°;  this  is  repeated  three 
times,  the  liquid  being  filtered  and  the  solid  material  expressed.  The 
united  extracts  are  evaporated  at  the  temperature  of  the  water-bath  to  a 
thin  syrup;  this  is  mixed  with  three  or  four  volumes  of  alcohol,  the  mix- 
ture kept  at  about  35°  for  twenty-four  hours,  cooled  well  and  filtered; 
the  residue  being  washed  with  seventy  per  cent,  alcohol.  The  alcohol  is 
distilled  from  the  filtrate,  and  the  watery  residue  diluted  with  water  and 
filtered. 

The  filtrate  so  obtained  contains  the  sulphates  of  the  alkaloids,  and 
from  it  the  alkaloids  themselves  are  separated  by  the  following  steps: 

First. — The  acid  watery  liquid  is  shaken  with  freshly  rectified  petro- 
leum ether  (which  should  boil  at  about  65° — 70°,  and  should  be  used  with 
caution,  as  it  is  very  inflammable);  after  several  agitations  the  ether  layer 
is  allowed  to  separate  and  is  removed;  this  treatment  is  repeated  so  long 
as  the  ether  dissolves  anything.  The  residue  obtained  by  the  evaporation 
of  the  ether — Residue  I.— is  mostly  composed  of  coloring  matters,  etc., 
which  it  is  desirable  to  remove. 

Second. — The  same  treatment  of  the  watery  liquid  is  repeated  with 
benzene,  which  on  evaporation  yields  Residue  II.,  which  is,  if  crystalline, 
to  be  tested  for  cantharidin,  santonin,  and  digitalin  (q.  i>.);  if  amorphous, 
for  elaterin  and  colchicin. 

Third. — The  acid,  aqueous  fluid  is  then  treated  in  the  same  way  with 
chloroform,  to  obtain  Residue  III.,  which  is  examined  for  cinchonine, 
digitalin,  and  picrotoxin  by  the  proper  tests. 

Fourth. — The  watery  fluid,  after  one  more  shaking  with  petroleum 
ether  and  removal  of  the  ethereal  layer,  is  rendered  alkaline  with  ammo- 
nium hydrate  and  shaken  with  petroleum  ether  at  40°,  the  ethereal  layer 
being  removed  as  quickly  as  possible  while  still  warm;  this  is  repeated 
two  or  three  times,  and  repeated  with  cold  petroleum  ether,  which  is  re- 


VOLATILE   ALKALOIDS.  349 

moved  after  a  time.  The  warm  ethereal  layers  yield  Residue  IVay  the 
cold  ones  Residue  IVb.  The  former  is  tested  for  strychnine,  quinine, 
brucine,  veratrine;  the  latter  for  coniine  and  nicotine. 

Fifth. — The  alkaline,  watery  fluid  is  shaken  with  benzene,  which,  on 
evaporation,  yields  Residue  V.,  which  may  contain  strychnine,  brucine, 
quinine,  cinchonine,  atropine,  hyoscyamine,  physostigmine,  aconitine,  co- 
deine, thebaine,  and  narceine. 

Sixth. — A  similar  treatment  with  chloroform  yields  Residue  VI.,  which 
may  contain  a  trace  of  morphine. 

Seventh. — The  alkaline  liquid  is  then  shaken  with  amyl  alcohol,  which 
is  separated  and  evaporated;  Residue  VII.  is  tested  for  morphine,  solanin 
and  salicin. 

Eighth. — Finally,  the  watery  liquid  is  itself  evaporated  with  pounded 
glass,  the  residue  extracted  with  chloroform,  and  Residue  VIII.,  left  by 
the  evaporation  of  the  chloroform,  tested  for  curarine. 


Volatile  Alkaloids. 

Coniine — Conicine — Cicutine — C8H15N — was  discovered  in  1827,  and 
is  obtained  from  Conium  maculatum,  in  which  it  is  accompanied  by  two 
other  alkaloids,  methyl-coni'ine,  C8H14N  (CH3),  and  conhydrin,  C9H17NO 
— the  former  a  volatile  liquid,  the  second  a  crystalline  solid. 

Coniine  is  a  colorless,  oily  liquid;  has  an  acid  taste  and  a  disagreeable 
penetrating  odor;  sp.  gr.  0.878;  can  be  distilled  when  protected  from 
air;  boils  at  212°;  exposed  to  air  it  resinifies;  it  is  very  sparingly  solu- 
ble in  water,  but  is  more  soluble  in  cold  than  in  hot  water;  soluble  in  all 
proportions  in  alcohol,  soluble  in  six  volumes  of  ether,  very  soluble  in 
fixed  and  volatile  oils. 

The  vapor  which  it  gives  off  at  ordinary  temperatures  forms  a  white 
cloud  when  it  comes  in  contact  with  a  glass  rod  moistened  with  hydro- 
chloric acid,  as  does  ammonia.  It  forms  salts  which  crystallize  with 
difficulty.  Chlorine  and  bromine  combine  with  it  to  form  crystallizable 
compounds;  iodine  in  alcoholic  solution  forms  a  brown  precipitate  in  al- 
coholic solutions  of  coniine,  which  is  soluble  without  color  in  an  excess. 
Oxidizing  agents  attack  coniine  with  production  of  butyric  acid  (see 
below).  The  iodides  of  ethyl  and  methyl  combine  with  coniine  to  form 
iodides  of  ethyl  and  methyl-conium.  It  has  been  obtained  synthetically 
by  first  allowing  butyric  aldehyde  and  an  alcoholic  solution  of  ammonia 
to  remain  some  months  in  contact  at  30°,  when  dibutyraldine  is  formed, 

2(C4H80)     +     NH3     =     C.HI7NO     +     H2O 

Butyric  Ammonia.  Dibutyraldine.  Water, 

aldehyde. 

The  dibutyraldine  thus  obtained  is  then  heated  under  pressure  to  150° — 
180°,  when  it  loses  water: 

C8H17NO     =     C8H1SN     +     H,0 

Dibutyraldine.  Coniine.  Water. 


350  GENERAL   MEDICAL   CHEMISTRY. 

A  synthesis  which,  in  connection  with  the   decompositions   of  coniine, 

<c.HT     . 

shows  its  rational  formula  to  be  (C4H7)'  V  N. 


The  characteristic  reactions  of  conime  are:  1st,  treated  with  dry  hy- 
drochloric acid  gas  it  turns  reddish  purple  and  then  deep  indigo-blue; 
the  aqueous  acid  of  sp.  gr.  1.12,  when  evaporated  from  confine  leaves  a 
greenish  blue,  crystalline  mass;  2d,  iodic  acid  forms  a  white  precipitate 
in  alcoholic  solutions  of  conii'ne;  3d,  with  sulphuric  acid  it  forms  a  sul- 
phate which  by  evaporation  of  the  acid  turns  red  and  then  green,  giving 
off  an  odor  of  butyric  acid. 

When  taken  internally  it  is  an  active  poison,  causing  death  by  as- 
phyxia, often  as  quickly  as  prussic  acid. 

Nicotine,  CIOH14N2  —  exists  in  tobacco  in  different  proportion  in  dif- 
ferent varieties,  from  two  per  cent,  to  eight  per  cent. 

It  is  a  colorless,  oily  liquid,  which  turns  brown  on  exposure  to  lisrht 
and  air;  has  a  burning,  caustic  taste  and  a  disagreeable,  penetrating 
odor;  it  distils  at  250°;  it  burns  with  a  luminous  flame;  sp.  gr.  1.027  at 
15°;  it  is  very  soluble  in  water,  alcohol,  the  fatty  oils,  and  ether;  the 
last-named  fluid  removes  it  from  its  aqueous  solution  when  the  two  are 
shaken  together;  it  absorbs  water  rapidly  from  moist  air.  Its  salts  are 
deliquescent  and  crystallize  with  difficulty. 

Its  principal  reactions  are:  1st,  an  ethereal  solution  of  iodine  added 
to  an  ethereal  solution  of  nicotine  separates  at  first  a  reddish  brown,  res- 
inoid  oil,  which  gradually  becomes  crystalline,  and  there  separate  from 
the  solution  crystalline  needles,  often  one  to  two  inches  long,  which  are 
ruby  red  by  transmitted,  and  dark  blue  by  reflected  light;  2d,  it  turns 
violet  when  heated  with  hydrochloric  acid;  3d,  it  is  colored  orange-yellow 
by  nitric  acid. 

Nicotine  is  an  active  poison,  being  fatal  to  dogs  in  doses  of  2  —  3 
drops,  by  causing  asphyxia.  It  is  interesting  in  the  history  of  toxi- 
cology as  having  been  used  in  a  case  of  criminal  poisoning,  for  the  inves- 
tigation of  which  Stas  devised  the  first  systematic  method  of  searching 
for  the  alkaloids. 

Fixed  Alkaloids. 

These  are  much  more  numerous  than  those  which  are  volatile,  and 
form  the  active  principles  of  a  great  number  of  poisonous  plants.  As  we 
are  yet  in  the  dark  as  to  the  constitution  of  these  bodies,  the  only  classi- 
fication which  we  can  adopt  is  the  temporary  one  based  upon  the  botanic 
characters  of  the  plants  from  which  they  are  derived. 


Opium  Alkaloids. 

Opium  is  the  inspissated  juice  of  the  capsules  of  the  poppy.  It  is  of 
exceedingly  complex  composition,  and  contains,  besides  a  neutral  body 
called  meconine,  probably  a  polyatomic  alcohol,  C10H10O4,  a  peculiar  acid, 
meconic  acid  (q.  v.),  lactic  acid,  gum,  albumen,  wax,  and  a  volatile  mat- 
ter— no  less  than  eighteen  different  alkaloids,  one  or  two  of  which,  how- 
ever, are  probably  formed  during  the  processes  of  extraction,  and  do  not 
pre-exist  in  opium. 


OPIUM    ALKALOIDS. 


351 


The  following  is  a  list  of   the  constituents  of  opium,  those  marked 
being  of  medical  interest: 


Name. 

Formula. 

d 

Percent,  in 
Constantino- 
ple opium. 

Name. 

Formula. 

Percent,  in 
Smyrna 
opium. 

Percent,  in 
Conptantino- 
ple  opium. 

*Meconic  acid.  . 
Lactic  acid   .    .  . 

C7H407 

cloH.oO, 
C17H1GNO3 
C17H19NO4 

ol.Hi,No! 

C19H21N03 

4.70 
1.25 
0.08 
10.30 

4.38 

0.30 
4.50 

Co  H  -\O 

Papaverine  

Ca.Ha.NO* 

1.00 



Meconine            . 

*  Morphine 

Meconidine  .... 
Cryptopine  

C21H:3N04 
C21H23N05 

— 



Pseudomorphine 
Hydrocotarnine  . 

"Codeine 

6.25 
0.15 

1.52 

*Narcotine    .... 
Lanth  opine  .... 
*Narceine  

C23H2lNo! 
C23H29N03 

1.30 
0.71 

3.47 
'6.42 

*Thebaine  
Protopine  

Rhaeadine  
Codamine 

02oH31N08 





Porphyroxine 

Morphine,  C17H19NO3  + Aq. — This  alkaloid  was  probably  obtained  in 
an  impure  form  by  Boyle  in  the  seventeenth  century.  In  1803  Seguin, 
Derosne,  and  Sertuerner  almost  simultaneously  obtained  crystalline  prin- 
ciples from  opium,  but  failed  to  recognize  their  basic  character;  it  was 
only  in  1817  that  Sertuerner  recognized  the  true  nature  of  morphine,  and 
was  thus  the  first  to  discover  a  vegetable  alkaloid. 

Morphine  crystallizes  in  colorless  prisms;  odorless,  but  very  bitter;  it 
fuses  at  120°,  losing  its  water  of  crystallization;  more  strongly  heated,  it 
swells  up,  becomes  carbonized,  and  finally  burns.  It  is  soluble  in  1000 
pts.  of  cold  water,  in  100  pts.  of  boiling  water;  in  20  pts.  of  alcohol  of 
0.82,  and  in  13  pts.  of  boiling  alcohol  of  the  same  strength;  in  390  pts.  of 
cold  amyl  alcohol,  much  more  soluble  in  the  same  liquid  warm;  almost 
insoluble  in  aqueous  ether;  rather  more  soluble  in  alcoholic  ether;  almost 
insoluble  in  benzene;  soluble  in  60  pts.  of  chloroform.  All  the  solvents 
dissolve  morphine  more  readily  and  more  copiously  when  it  is  freshly  pre- 
cipitated from  solutions  of  its  salts  than  when  it  has  assumed  the  crystal- 
line form. 

Morphine  combines  with  acids  to  form  crystallizable  salts,  of  which  the 
chloride,  sulphate,  and  acetate  are  used  in  medicine.  The  action  of  hy- 
drochloric acid  upon  morphine  is  interesting;  if  morphine  be  heated  for 
some  hours  with  excess  of  hydrochloric  acid,  under  pressure,  to  150°,  it 
loses  water  and  is  converted  into  a  new  base — apomorphiney  C17H17NO2 — 
a  valuble  emetic,  which  may  be  administered  hypodermically.  It  is  a  crys- 
talline solid,  soluble  in  ether. 

Tests  for  morphine. — 1st.  Nitric  acid  colors  it  red,  changing  to  yel- 
low. 2d.  If  a  fragment  of  morphine  be  moistened  with  cold  concentrated 
sulphuric  acid  and  allowed  to  stand  twenty-four  hours,  a  colorless  solution 
remains,  which  turns  pink  or  red  on  the  addition  of  a  trace  of  nitric  acid. 
If,  as  is  almost  invariably  the  case,  the  sulphuric  acid  contain  nitric 
acid,  the  red  color  is  produced  without  addition  of  nitric  acid.  The  fluid, 
when  warmed,  cooled,  and  diluted  with  water,  turns  deep  mahogany  brown 
on  the  addition  of  a  splinter  of  potassium  dichromate.  3d.  A  mixture  of 
morphine  and  cane-sugar  (one  to  four)  added  to  concentrated  sulphuric 
acid,  communicates  to  it  a  dark  red  color,  which,  when  dealing  with  very 
small  quantities  of  morphine,  can  be  brought  out  by  the  addition  of  a  drop 


352  GENERAL    MEDICAL    CIIEMISTKY. 

of  bromine  water.  4th.  Morphine  reduces  solutions  of  iodic  acid  with  liber- 
ation of  iodine.  The  test  is  best  applied  by  adding  to  the  morphine  resi- 
due, on  a  watch-glass,  a  drop  or  two  of  chloroform,  then  a  few  drops  of  a 
solution  of  iodic  acid,  and  stirring;  if  morphine  be  present,  the  chloroform 
is  colored  violet.  This  reaction  is  quite  delicate,  and,  in  the  absence  of 
other  reducing  agents,  characteristic  of  morphine,  as  it  is  not  brought 
about  by  any  other  vegetable  alkaloid.  5th.  A  neutral  solution  of  a  mor- 
phine salt  colors  neutral  solution  of  fejrric  chloride  a  deep  blue.  6th.  If  a 
solution  of  molybdic  acid  in  sulphuric  acid  (Frohde's  reagent)  be  added  to 
a  trace  of  morphine  or  of  a  morphine  salt,  it  is  colored  a  beautiful  violet 
by  the  reduction  of  the  molybdenum  compound;  the  color  gradually 
changes  to  blue,  then  to  a  dirty  green,  and  finally  to. a  very  faint  pink;  it 
is  instantly  discharged  on  the  addition  of  water.  7th.  A  solution  of  ace- 
tate of  morphine,  warmed  with  an  ammoniacal  solution  of  silver  nitrate, 
produces  a  gray  precipitate  of  metallic  silver;  the  filtrate  turns  red  or  pink 
on  the  addition  of  nitric  acid.  8th.  Auric  chloride  forms,  with  solutions 
of  morphine,  a  yellow  precipitate,  which  subsequently  turns  violet-blue. 

Codeine,  C18H21NO3  +  Aq. — crystallizes  in  large  rhombic  prisms,  or, 
from  ether  without  water  of  crystallization,  in  octahedra;  it  is  bitter;  sol- 
uble in  80  pts.  of  cold  water,  17  pts.  of  boiling  water;  very  soluble  in  al- 
cohol, ether,  chloroform,  benzene;  almost  insoluble  in  petroleum  ether; 
fuses  at  158°. 

It  dissolves  in  cold,  concentrated  sulphuric  acid,  the  solution  being 
colorless,  but  assuming  a  blue  color  after  several  days,  or  immediately  on 
being  warmed.  Frohde's  reagent  (see  Morphine)  dissolves  it  with  a  dirty 
green  color,  which,  after  a  time,  turns  to  blue.  Neutral  solution  of  ferric 
chloride  is  only  colored  blue  by  it  after  the  addition  of  sulphuric  acid.  It 
combines  with  iodine  to  form  a  ruby-red  or  violet  compound. 

Codeine  is  probably  derived  from  morphine  by  the  substitution  of 
methyl  (OH,)  for  an  atom  of  hydrogen,  C17H18  (CH3)NO3-C18H21NO3,  be- 
cause, by  acting  upon  codeine  with  hydrochloric  acid,  as  in  the  formation 
of  apomorphine  from  morphine,  that  base  is  formed  along  with  methyl 
chloride : 

C18H21NO3    +    HC1    =    CnH17N02    +    H20    +    CH.C1 

Codeine.          Hydrochloric  acid.      Apomorphine.  Water.          Methyl  chloride. 

Narceine,  C23H09NO9  +  2  Aq. — crystallizes  in  fine,  prismatic  needles; 
bitter;  sparingly  soluble  in  water,  alcohol,  and  amyl  alcohol — much  more 
soluble  in  the  same  solvents  when  warm;  insoluble  in  ether,  benzene,  and 
petroleum  ether;  it  fuses  at  92°;  at  100°  it  loses  1  Aq.,  and  the  other  at 
140°;  at  which  temperature  it  is  decomposed  into  amorphous  products. 

It  dissolves  in  concentrated  sulphuric  acid  with  a  gray-brown  color, 
which,  slowly  at  ordinary  temperatures,  rapidly  when  heated,  changes  to 
blood-red.  Frohde's  reagent  colors  it  first  dark  olive-green,  which  passes 
after  a  time,  or,  when  heated,  to  red;  if  an  incipient  red  color  have  been 
obtained  by  heating  the  mixture,  it  on  cooling  gradually  turns  blue,  be- 
ginning at  the  edges.  It  is  colored  blue-violet  by  iodine  solution,  like 
starch.  A  solution  of  iodine  in  potassium  iodide  solution  causes,  in  nar- 
ceine  solutions,  an  amorphous  brown  precipitate,  which,  after  a  time,  be- 
comes crystalline  and  lighter  in  color. 

Narcotine,  C22H23NO7 — crystallizes  readily  in  transparent  prisms; 
fuses  at  177°,  and,  when  fused,"crystallizes  at  130°,  and  at  220°  it*  is  de- 
composed, ammonia  is  given  off,  and  hemipinic  acid,  C20HJCO12,  remains; 


CINCHONA   ALKALOIDS.  353 

it  is  almost  insoluble  in  water,  readily  soluble  in  alcohol,  ether,  and  ben- 
zene, insoluble  in  petroleum  ether,  and  in  water  faintly  acidulated  with 
acetic  acid;  chloroform  removes  it  from  its  hydrochloric  acid  solution 
when  the  two  are  shaken  together. 

Its  salts  are  for  the  most  part  uncrystallizable,  unstable,  and  readily 
soluble  in  water  and  alcohol.  Concentrated  sulphuric  acid  dissolves  it, 
the  solution  being  at  first  colorless,  but  turns  yellow  in  a  few  moments, 
and  finally,  after  a  day  or  two,  red.  Its  solution  in  dilute  sulphuric  acid 
if  very  gradually  evaporated,  turns  first  orange-red,  and  then,  from  the 
periphery  toward  the  centre,  bluish  violet,  and  finally,  when  the  acid  be- 
gins to  volatilize,  reddish  violet.  A  solution  of  narcotine  in  cold  con- 
centrated sulphuric  acid  is  colored  red  by  the  introduction  of  a  trace  of 
nitric  acid;  if  the  sulphuric  acid  contain  nitric  acid,  the  red  color  appears 
on  dissolving  the  alkaloid.  Frohde's  reagent  dissolves  it  with  a  greenish 
color,  passing  to  cherry-red. 

Thebaine — Paramorphine — CiaHyiNO8 — probably  the  most  actively 
poisonous  of  the  opium  alkaloids,  crystallizes  in  white,  silvery  plates; 
fuses  at  93°;  is  without  taste  when  pure;  insoluble  in  water,  soluble  in 
alcohol,  ether,  and  benzene;  its  salts  are  readily  soluble  in  water  and 
alcohol. 

Concentrated  sulphuric  acid  is  immediately  colored  bright  red  by  it, 
the  solution  gradually  turning  yellowish  red.  Chlorine,  bromine,  and 
nitric  acid  attack  it  energetically.  Frohde's  reagent  behaves  with  it  like 
sulphuric  acid.  Sulphuric  acid  containing  nitric  acid  is  colored  reddish 
orange  by  it.  Its  solution  in  chlorine  water  is  colored  dark  reddish  brown 
by  ammonia. 

Meconic  acid,  C7H4O7-f-3Aq. — a  tribasic  acid  existing  in  opium  in 
combination  with  a  part,  at  least,  of  the  alkaloids.  It  is  obtained  from 
the  calcic  meconate  resulting  from  the  preparation  of  morphine.  It  crys- 
tallizes in  small  prismatic  needles;  has  an  acid,  astringent  taste;  loses 
its  water  of  crystallization  at  120°;  quite  soluble  in  water,  soluble  in  al- 
cohol, sparingly  soluble  in  ether. 

The  characteristic  reaction  of  meconic  acid  is  the  production  of  a 
blood-red  color  with  ferric  chloride;  the  color  is  not  discharged  by  dilute 
acids  or  by  mercuric  chloride,  but  is  discharged  by  stannous  chloride  and 
by  alkaline  hypochlorites  (see  p.  341). 

The  reactions  of  meconic  acid  and  of  narcotine  are  of  great  value  to 
the  toxicologist  in  enabling  him  to  distinguish  between  poisoning  by 
morphine  and  that  by  opium  or  its  preparations. 


Cinchona  Alkaloids. 

Although  by  no  means  so  complex  as  opium,  cinchona  bark  contains 
a  great  number  of  substances:  quinine,  cinchonine,  quinidine,  cinchoni- 
dine,  aricine;  quinic,  quinotannic,  and  quinovic  acids;  cinchona  red,  etc. 
Of  these  the  most  important  are  quinine  and  cinchonine. 

Quinine,  C20H21N2Oa+nAq.— discovered  in  1820,  by  Pelletier  and 
Caventou.  It  exists  in  the  bark  of  a  variety  of  trees  of  the  genera  Cin- 
chona and  China,  indigenous  in  the  mountainous  regions  of  the  north  of 
South  America,  which  vary  considerably  in  their  richness  in  this  alkaloid, 
and  consequently  in  value;  the  best  samples  of  calisaya  bark  contain 
from  30  to  32  parts  per  1,000  of  the  sulphate;  the  poorer  grades  4  to  20 
23 


354  GENERAL   MEDICAL    CHEMISTRY. 

parts  per  1,  000;  inferior  grades  of  bark  contain  from  mere  traces  to  G 
parts  per  1,000. 

It  is  known  in  three  different  states  of  hydration,  with  one,  two,  and 
three  molecules  of  water,  and  anhydrous.  The  anhydrous  form  is  an 
amorphous,  resinous  substance,  obtained  by  evaporation  of  solutions  in 
anhydrous  alcohol  or  ether.  The  first  hydrate  is  obtained  in  crystals  bv 
exposing  to  air  recently  precipitated  and  well-washed  quinine;  the  secon'd 
by  precipitating  by  ammonia  a  Solution  <yf  quinine  sulphate,  in  which  hy- 
drogen has  been  previously  liberated  by  the  action  of  zinc  upon  sulphuric 
acid;  it  is  a  greenish,  resinous  body,  which  loses  H2O  at  150°.  The 
third,  that  to  which  the  following  remarks  apply,  is  formed  in  the  pro- 
cesses of  manufacture  by  precipitating  solutions  of  quinine  salts  with 
ammonia. 

It  crystallizes  in  hexagonal  prisms;  is  very  bitter;  fuses  at  120°; 
becomes  colored,  swells  up,  and,  finally,  burns  with  a  smoky  flame.  It 
does  not  sublime.  It  dissolves  in  2,200  pts.  of  cold  water,  in  ?GO  of  hot 
water;  very  soluble  in  alcohol  and  chloroform;  soluble  in  amyl  alcohol, 
benzene,  fatty  and  essential  oils,  and  ether.  Its  alcoholic  solution  is 
powerfully  Isevogyrous,  according  to  the  most  recent  observations  the 
value  of  [&]D=—  270.7°  at  18°,  which  is  diminished  by  increase  of  tem- 
perature, but  increased  by  the  presence  of  acids. 

The  decompositions  of  quinine,  although  of  great  interest  to  the 
chemist  as  affording  indications,  slight  at  present,  which  may  load  to  its 
artificial  production,  are  of  little  direct  interest  in  this  place. 

Dilute  sulphuric  acid  dissolves  quinine,  forming  colorless,  but  fluores- 
cent solutions  (see  below).  Quinine,  or  its  salts,  in  solution,  is  colored 
green  when  treated  first  with  chlorine,  and  then  with  ammonia.  A  cur- 
rent of  chlorine  passed  through  water  holding  quinine  in  suspension, 
forms  a  red  solution.  A  solution  of  quinine  treated  with  chlorine  water, 
and  then  with  some  fragments  of  potassium  ferrocyanide,  is  colored  pink, 
passing  to  red. 

Quinine  is  not  used  in  medicine  in  the  free  state,  but  in  the  form  of 
its  salts,  the  most  important  of  which  are: 

Sulphate — Disulphate — Quinice  sulphas — (U.  S.,  Br.) — SO4  (CaoHM 
N2O2)2  -+-  7  Aq. — is  the  form  usually  met  with.  It  crystallizes  in  pris- 
matic needles;  very  light;  intensely  bitter;  phosphorescent  when  heated 
to  100°;  fuses  readily,  loses  its  water  of  crystallization  at  120°,  turns  red, 
and  finally  carbonizes;  it  effloresces  on  contact  with  air,  losing  6  Aq. ; 
soluble  in*740  pts.  of  water  at  13°,  and  in  30  pts.  of  boiling  water;  in  60 
pts.  of  alcohol;  almost  insoluble  in  ether. 

Its  solution,  mixed  with  an  alcoholic  solution  of  iodine,  deposits  a 
brilliant  green  crystalline  compound.  Quinine  sulphate,  in  the  presence 
of  water,  treated  with  an  excess  of  dilute  sulphuric  acid,  is  dissolved,  the 
solution  containing  the 

Hydrosulphate,  SO4H  (CQOH34N2O2)  -f  7  Aq. — which  is  consequently 
the  salt  present  in  most  medicinal  solutions  of  quinine.  It  may  be  crys- 
tallized in  long,  silky  needles,  or  in  short,  rectangular  prisms.  It  differs 
from  the  preceding  salt  in  its  much  greater  solubility  in  water,  being  dis- 
solved by  11  pts.  of  that  solvent  at  13°.  Its  solutions  exhibit  in  a 
marked  manner  the  phenomena  of  fluorescence,  being  colorless,  but  show- 
ing a  fine,  pale  blue  color  when  illuminated  by  a  bright  light  against  a 
dark  background,  or  by  transmitted  light. 

Bisulphate,  C20H24N2O2  (SO4H2)2  H-  7  Aq. — a  compound  obtained  by 
evaporating  a  solution  of  the  preceding  salt  in  the  presence  of  an  excess 


CINCHONA   ALKALOIDS.  355 

of  moderately  concentrated  sulphuric  acid.  It  forms  white,  prismatic 
needles;  very  soluble  in  water;  is  colored  reddish  brown  by  exposure  to 
light;  its  solution  is  highly  fluorescent. 

Owing  to  the  high  price  of  the  salts  of  quinine,  they  are  largely  adul- 
terated. Pure  quinine  should  respond  to  the  following  tests:  when  a 
gram  of  it  is  shaken  up  in  a  test-tube  with  15  c.c.  of  ether  and  2  c.c.  of 
aqua  ammonias,  the  liquids  should  subsequently  separate  into  two  clear 
layers,  without  any  milky  zone  between  them  (cinchonine).  When  dis- 
solved in  hot  water,  precipitated  with  an  alkaline  oxalate  and  filtered,  the 
filtrate  should  not  precipitate  with  ammonia  (quinidine).  It  should  be 
completely  soluble  in  water  acidulated  with  sulphuric  acid  (fats,  resins). 
It  should  dissolve  completely  in  dilute,  boiling  alcohol  (gum,  starch,  alka- 
line and  earthy  salts).  It  should  not  be  blackened  by  sulphuric  acid 
(cane-sugar).  It  should  not  be  colored  red  or  yellow  by  sulphuric  acid 
(salicin  and  phlorizin).  When  burned  upon  platinum  foil,  it  should  leave 
no  residue  (mineral  substances). 

Cinchonine — C20H24N2O — accompanies  quinine  in  Peruvian  bark,  in 
which  it  is  present  in  less  amount,  varying  from  2  to  12  pts.  per  1,000; 
and  in  some  cases,  as  in  yellow  Guayaquil  bark,  reaching  30  pts.  per  1,000. 

It  crystallizes  in  colorless  prisms  or  needles  without  water  of  crystal- 
lization; fuses  at  150°,  and  at  220°  is  partly  sublimed  in  fine  needles  and 
partly  decomposed;  it  is  soluble  in  3,810  pts.  of  water  at  10°,  in  2,500 
pts.  of  boiling  water;  in  140  pts.  of  alcohol  of  sp.  gr.  0.852  at  10°;  in 
371  pts.  ether  at  20°;  in  40  pts.  chloroform;  dextrogyrous,  [a]  — -f- 190.4°; 
alkaline;  bitter. 

Although  cinchonine  differs  from  quinine  in  composition  only  by  one 
atom  of  oxygen  less,  all  attempts  to  convert  the  former  into  the  latter 
alkaloid  by  oxidation  have  only  resulted  in  the  formation  of  an  isomere 
of  quinine — oxy  cinchonine. 

The  salts  of  cinchonine  resemble  those  of  quinine  in  composition,  but 
differ  from  them  in  being  much  more  soluble  in  water  and  alcohol,  and 
in  not  being  fluorescent;  they  are  permanent  in  air,  and  become  phos- 
phorescent when  heated  to  100°. 

Two  other  alkaloids  derived  from  plants  related  to  the  cinchona  re- 
quire mention. 

Caffeine — TJieine — Guaranin — C8H10N4O2  -f  Aq. — exists  in  coffee, 
tea-leaves,  Paraguay  tea,  and  other  plants. 

It  crystallizes  in  long,  silky  needles;  faintly  bitter;  soluble  in  93  pts. 
of  water  at  12°,  158  pts.  strong  alcohol,  or  218  pts.  ether.  Hot,  fuming 
nitric  acid  converts  it  into  a  yellow  liquid,  which  turns  purple  on  the  addi- 
tion of  ammonia;  on  boiling,  the  mixture  is  decolorized  and  white  crystals 
of  cholestrophane,  a  methyl  derivative  of  parabanic  acid  (q.  v.)y  separate. 
Chlorine  acting  on  caffeine  in  the  presence  of  water,  yields  a  methyl  de- 
rivative of  alloxantine  (q.  v.) — amalic  acid. 

Emetine — C30H44N2O8 — a  poisonous  alkaloid  to  which  ipecacuanha 
owes  its  activity.  It  appears  as  a  white,  amorphous,  somewhat  bitter  pow- 
der, almost  insoluble  in  cold  water;  sparingly  soluble  in  hot  water,  alco- 
hol, chloroform,  and  ether;  soluble  in  benzene  and  petroleum  ether. 

Concentrated  sulphuric  acid  forms  with  it  a  greenish  brown  solution. 
Sulphuric  acid  containing  nitric  acid  colors  it  green,  changing  to  yellow. 
Frohde's  reagent  dissolves  it  immediately  with  a  red  color,  passing  soon 
to  a  yellowish  green,  then  to  green. 


356  GEKEKAL    MEDICAL    CHEMISTRY. 


Alkaloids  of  the  LoganiaceaB. 

Strychnine,  C21H22N2O2 — discovered  in  1818  by  Pelletier  and  Caven- 
tou,  in  the  St.  Ignatius  bean  and  subsequently  in  other  varieties  of 
Strychiios.  The  sources  from  which  the  alkaloid  is  now  almost  exclusively 
obtained  are  the  seeds  of  the  Strychnos  nux  vomicay  and  the  bark  of  the 
same  tree,  known  as  false  Angostura  bark  •  the  seeds  contain  about  0.5 
per  cent  of  strychnine. 

Strychnine  crystallizes  upon  spontaneous  evaporation  of  its  solutions 
in  orthorhombic  prisms;  by  rapid  evaporation  or  sudden  cooling  of  its 
solutions  it  separates  as  a  white  powder.  Its  solutions  are  alkaline  in  re- 
action and  have  an  intensely  bitter  taste,  which  is  perceptible  in  a  solu- 
tion containing  only  1  part  in  600,000.  It  is  very  sparingly  soluble 
in  water  (in  6,067  parts  of  cold  and  in  2,500  parts  of  warm  water).  Its 
solubility  in  alcohol  varies  with  the  strength  of  the  solvent;  it  is  insolu- 
ble in  absolute  alcohol;  1  part  of  strychnine  is  soluble  in  120  parts  of 
alcohol  of  sp.  gr.  0.863  at  the  ordinary  temperature,  and  in  10  parts  of  the 
same  alcohol  at  the  boiling-point;  a  weaker  alcohol,  of  sp.  gr.  0.936  dis- 
solves 1  part  in  240  in  the  cold.  It  is  insoluble  in  absolute  ether,  very 
sparingly  soluble  in  commercial  ether.  Benzene  and  amyl  alcohol  dissolve 
1  part  to  200-250.  Its  best  solvent  is  chloroform,  which  is  capable  of 
dissolving  twenty  per  cent,  of  strychnine.  It  is  also  sparingly  soluble  in 
creasote,  the  fatty  and  volatile  oils,  glycerin,  and  carbon  disulphide. 
From  most  of  these  solutions  it  may  be  obtained  in  the  crystalline  form 
by  evaporation.  The  alcoholic  solutions  are  Inevogyrous,  [«]  j  =  — 132° — 
136°;  the  acid  solutions  are  much  less  active.  Strychnine  cannot  be 
fused  without  undergoing  decomposition,  and  is  only  partially  capable  of 
sublimation. 

Strychnine  is  a  powerful  base;  it  neutralizes  the  strongest  acids,  being 
dissolved  (with  formation  of  a  sulphate)  without  decomposition  in  con- 
centrated sulphuric  acid;  it  also  precipitates  many  metallic  oxides  from 
solutions  of  the  corresponding  salts. 

The  salts  of  strychnine  are  for  the  most  part  crystallizable,  soluble  in 
water  and  in  alcohol,  and  are  all  intensely  bitter.  Of  the  salts  of  strych- 
nine the  neutral  sulphate,  SO4H2  (C21H22N202)2-h7Aq.,  is  generally  used 
medicinally  in  place  of  the  alkaloid;  it  crystallizes  in  rectangular  prisms, 
soluble  in  ten  parts  of  water;  the  water  of  crystallization  is  driven  off  by 
heat  or  in  vacuo.  The  acetate  is  exceedingly  soluble  in  water,  and  only 
crystallizes  in  the  presence  of  an  excess  of  acid. 

By  the  action  of  chlorine  upon  solutions  of  strychnine,  compounds  are 
obtained  in  which  one  or  three  atoms  of  hydrogen  are  replaced  by  atoms 
of  chlorine;  these  chlorine  derivatives  possess  basic  properties.  By  the 
action  of  iodine  upon  strychnine,  a  peculiar  substance  called  iodostrych- 
nine,  4021H22N202,3I2,  is  obtained,  which  crystallizes  in  alcoholic  fluids  in 
golden  yellow  scales. 

The  iodides  of  methyl  and  of  ethyl  react  energetically  with  strychnine, 
to  form  the  iodides  of  methyl  or  ethylstrychnium,  which  bear  the  same 
relation  to  the  alkaloid  that  the  iodide  of  ammonium  bears  to  ammonia. 
These  substances  are  white,  crystalline  solids,  basic  in  their  nature,  which 
in  common  with  similar  derivatives  of  other  alkaloids  possess  the  power, 
when  injected  subcutaneously,  of  producing  effects  very  similar  to  those 
of  curarine  (q.  v.). 

By  the  action  of  potassium  nitrite  upon  a  boiling  aqueous  solution  of 


ALKALOIDS    OF    THE    LOGANIACEuE.  357 

strychnine  sulphate,  nitrogen  is  given  off  and  two  oxidized  products  are 
formed;  one,  which  crystallizes  in  fine  orange-yellow  crystals,  is  oxystrych- 
nine,  C21IL8N  O  ;  the  other,  forming  red  crystals,  is  bioxy strychnine,  C21 
H28N307.  ' 

When  strychnine  is  acted  upon,  with  proper  precautions,  by  sulphuric 
acid  and  potassium  chlorate,  a  crystallizable  acid  called  strychnic  acid  is 
formed;  it  seems  to  be  the  same  substance  which,  under  the  name  igasurie 
acid,  has  been  obtained  from  St.  Ignatius'  beans,  and  with  which  the 
alkaloid  is  probably  in  combination  in  nature. 

Tests  for  strychnine. — 1st.  It  dissolves  without  decomposition  in  con- 
centrated sulphuric  acid,  the  solution  being  colorless  if  the  alkaloid  be 
pure.  The  alkaloid  is  precipitated  when  the  solution  is  diluted  and  the 
acid  is  neutralized,  preferably  with  magnesia  in  very  slight  excess.  2d. 
When  a  fragment  of  any  substance,  capable  of  yielding  nascent  oxygen 
on  contact  with  concentrated  sulphuric  acid,  is  added  to  a  solution  of 
strychnine  in  that  acid,  the  following  colors  appear:  a  very  transitory 
blue  (frequently  not  perceptible);  a  brilliant  violet,  which  slowly  changes 
to  rose-pink,  and  this  in  turn  to  yellow.  Of  the  various  oxidizing  agents 
which  have  been  recommended,  we  believe  potassium  dichromate  to  be  the 
best  for  the  purposes  of  this  test,  notwithstanding  the  opposite  opinion, 
expressed  by  Letheby  and  echoed  verbatim  by  Woodman  and  Tidy. 

The  test  is  best  applied  by  evaporating,  upon  a  procelain  dish  or  a  watch- 
glass  (when  the  latter  is  used  it  must  be  placed  upon  a  white  surface 
when  the  dichromate  is  added),  a  drop  or  two  of  the  solution  suspected 
of  containing  strychnine;  the  residue  is  treated  with  one  or  two  drops 
of  concentrated  sulphuric  acid,  which  is  spread  out  with  a  glass  rod;  a 
small  fragment  (not  powder)  of  potassium  dichromate  is  then  placed  upon 
a  dry  part  of  the  watch-glass  and  pushed  with  moderate  rapidity  from  one 
part  of  the  moistened  surface  to  another;  if  strychnine  be  present,  the 
course  of  the  dichromate  will  be  marked  by  a  violet  streak,  which  passes 
through  rose-pink  to  yellow. 

This  reaction  is  of  great  delicacy,  being  capable  of  showing  the  pres- 
ence of  -g^i^j  grain  of  strychnine,  and  if  applied  to  a  residue  suitably  ob- 
tained (see  p.  348),  is  characteristic  of  the  alkaloid.  The  only  known 
substance,  in  fact,  which  produces  the  same  play  of  colors  under  like  con- 
ditions, is  curarine;  but,  as  this  substance  is  quite  soluble  in  water  and 
does  not  pass  from  its  alkaline  aqueous  solution  into  the  solvents  used  in 
the  process  of  separation,  it  cannot  find  its  way  into  the  solutions  in 
\yhich  strychnine  is  soi^ht  for,  and  cannot,  therefor,  give  rise  to  any  error. 
A  somewhat  similar  reaction  is  produced  by  aniline,  which  may,  how- 
ever, be  readily  distinguished  from  strychnine  by  its  being  liquid  or  oily, 
while  strychnine  is  solid;  by  its  peculiar  odor,  strychnine  being  odorless;- 
and  by  the  fact  that  the  reaction  only  takes  place  with  dilute  sulphuric 
acid  in  the  case  of  aniline,  and  with  the  concentrated  acid  in  the  case  of 
strychnine.  The  presence  of  morphine  also  interferes  to  a  certain  extent 
with  the  action  of  this  test,  an  interference  which  is,  however,  of  but 
slight  practical  importance,  as  morphine  is  not  found  in  the  same  residue 
as  strychnine  (p.  349).  In  the  presence  of  brucine  the  reaction  takes 
place  more  slowly,  the  color  only  appearing  after  oxidation  of  the  brucine. 
3d.  A  dilute  solution  of  potassium  dichromate  produces  in  solutions 
of  strychnine  a  yellow  crystalline  precipitate  of  strychnine  chromate. 
Otto  utilizes  the  formation  of  this  salt  for  the  production  of  the  color  re- 
action (2);  he  advises  that  the  residue  containing  strychnine  be  mois- 
tened with  dilute  solution  of  potassium  dichromate  (1  in  200);  after  a 


358  GENERAL    MEDICAL    CHEMISTKY. 

few  moments  the  fluid  is  poured  off,  the  deposit  washed,  and  treated  with 
concentrated  sulphuric  acid,  when  the  characteristic  play  of  colors  is  ob- 
served. 4th.  If  a  solution  of  strychnine  be  evaporated  in  a  depression 
in  a  strip  of  platinum  foil,  the  residue  moistened  with  concentrated  sul- 
phuric acid,  the  foil  connected  with  the  positive  pole  of  a  single  cell  of 
Grove's  or  Smee's  battery,  and  a  platinum  wire  from  the  negative  pole 
brought  in  contact  with  the  surface  of  the  acid,  a  violet  color  appears 
upon  the  surface  of  the  foil  (Letheby).  £th.  Solutions  of  strychnine  arid 
of  its  salts  are  intensely  bitter,  the  taste  being  distinguishable  in  a  solu- 
tion containing  one  part  of  the  alkaloid  in  six  hundred  thousand  of  water. 
6th.  If  a  solution  of  strychnine  be  introduced  beneath  the  skin  of  the  back  of 
a  frog,  the  animal  exhibits  the  symptoms  of  strychnine-poisoning:  difficulty 
of  respiration;  tetanic  convulsions  induced  by  the  slightest  irritation,  as  by 
striking  the  table  or  blowing  upon  the  animal;  twitching  of  the  muscles 
during  the  intervals  between  the  convulsions;  dilatation  of  the  pupils 
during  the  convulsions,  and  contraction  during  the  intervals;  usually  em- 
prosthotonos,  sometimes  opisthotonos.  The  smallest  frogs  should  be 
selected,  and  they  should  be  dried  with  bibulous  paper  before  the  injec- 
tion of  the  solution.  This  test,  which  was  first  suggested  by  Marshall 
Hall,  is  very  delicate;  yro!5ir  gr&m  of  the  acetate  (— 1g}66  strychnine)  in- 
jected into  a  small  frog  have  produced  tetanic  spasms  in  nine  and  one-half 
minutes,  and  death  in  two  hours.  7th.  When  solid  strychnine,  or  a  residue 
containing  it,  is  moistened  with  a  solution  of  iodic  acid  in  sulphuric  acid 
a  yellow  color  appears,  which  soon  changes  to  brick-red,  and  finally  to  a 
violet-red  (Selmi).  8th.  Moderately  concentrated  nitric  acid,  in  the  cold, 
colors  strychnine  yellow;  a  pink  or  red  color  indicates  the  presence  of 
brucine. 

Strychnine  is  one  of  the  most  stable  of  the  alkaloids,  and  may  remain 
for  a  long  time  in  contact  with  putrefying  animal  matter  without  under- 
going decomposition. 

Antidotes. — Chloroform,  emetics,  the  stomach-pump,  chloral  hydrate. 

Brucine,  C23H26N2O4 — discovered  in  1819  by  Pelletier  and  Caventou, 
is  obtained  from  the  alcoholic  washings  in  the  preparation  of  strychnine. 
It  forms  transparent,  oblique,  rhomboidal  prisms,  containing  four  mole- 
cules of  water  of  crystallization,  which  are  readily  given  off  by  exposure 
to  dry  air.  It  fuses  a  little  above  100°,  and,  on  cooling,  forms  an  amor- 
phous, waxy  mass.  Effloresced  brucine  dissolves  in  500  pts.  of  boiling, 
and  in  850  pts.  of  cold  water;  the  newly  crystallized  alkaloid  is  more 
soluble;  it  is  easily  soluble  in  alcohol,  chloroform,  Ind  amylic  alcohol;  less 
soluble  in  benzene,  benzine,  glycerin,  and  the  volatile  oils;  insoluble  in 
ether  and  in  the  fatty  oils.  It  is  odorless,  intensely  and  persistently 
bitter. 

Brucine  is  a  powerful  base,  forming  salts  which  are,  for  the  most  part, 
crystallizable  and  soluble  in  water.  It  forms  compounds  similar  to  methyl-, 
ethyl-,  and  iodo-strychnine  under  like  conditions.  Its  action  upon  the 
animal  economy  is  similar  to  that  of  strychnine,  but  much  less  energetic. 

Tests  for  brucine. — 1st.  Concentrated  nitric  acid  gives  with  brucine  a 
bright  scarlet  color,  which  soon  assumes  a  yellowish  tinge,  and  finally  be- 
comes yellow,  especially  if  heated;  upon  the  addition  of  stannous  chlo- 
ride or  of  colorless  ammonium  sulphydrate  to  the  red  fluid,  it  is  turned 
to  an  intense  violet.  2d.  A  solution  of  brucine  assumes  a  bright  red 
color  upon  the  addition  of  chlorine  water  or  of  chlorine  gas,  the  color  chang- 
ing to  yellowish  brown  upon  the  addition  of  ammonium  hydrate. 

The  separation  of  brucine  from  strychnine  is  best  effected  by  adding 


ALKALOIDS  FROM  OTHER  SOURCES.  359 

to  a  solution  of  the  mixed  acetates,  not  too  dilute,  a  solution  of  potassium 
dichrornate  ;  the  strychnine  is  precipitated  as  the  chromate,  while  the 
brucine  remains  in  the  solution. 

Igasurine — an  alkaloid  discovered  in  nux  vomica  by  Desnoix.  In 
poisonous  activity  it  is  intermediate  between  strvchnine  and  brucine,  which 
alkaloids  it  resembles  in  the  nature  of  its  action  upon  the  economy. 

Curarine,  C10H15N — an  alkaloid  obtained  from  curare  or  worara,  a 
South  American  arrow-poison.  It  crystallizes  in  four-sided,  hygroscopic 
prisms;  very  bitter;  faintly  alkaline;  very  soluble  in  water  and  in  alcohol; 
insoluble  in  ether  and  benzene. 

Concentrated  sulphuric  acid  colors  it  blue;  upon  the  addition  of  a  crys- 
tal of  potassium  dichromate  to  this  solution,  the  same  changes  of  color  as 
with  strychnine  (q.  v.)  are  observed,  but  they  take  place  more  slowly. 
Nitric  acid  colors  it  purple. 


Alkaloids  of  the  Solanaceae. 

* 

The  alkaloids  of  this  class  are  solanine,  dulcamarine,  atropine,  bella- 
donine,  hyoscyamine,  lycine,  and  duboisine. 

Solanine,  C43II69NO16 — obtained  from  many  species  of  Solarium.  It 
crystallizes  in  small,  white,  shining  prisms;  faintly  bitter  and  nauseous  in 
taste;  sparingly  soluble  in  water,  alcohol,  and  ether. 

Concentrated  sulphuric  acid  colors  it  orange-red,  passing  to  violet  and 
then  to  brown.  Nitric  acid  colors  it  yellow. 

Atropine — Daturine — C17H23NO3 — is  the  active  principle  of  bella- 
donna. It  crystallizes  in  colorless  needles;  strongly  and  persistently  bit- 
ter; alkaline;  sparingly  soluble  in  water,  benzene,  and  ether;  very  sol- 
uble in  chloroform;  it  volatilizes  when  its  solutions  and  those  of  its  salts 
are  boiled.  If  a  fragment  of  potassium  dichromate  be  dissolved  in  a  few 
drops  of  concentrated  sulphuric  acid,  the  mixture  warmed,  a  fragment  of 
atropine,  and  then  a  drop  or  two  of  water  added,  the  mixture  being  stirred, 
an  odor  resembling  that  of  orange-blossoms  is  observed. 

Hyoscyamine,  C15H}7NO  (?) — the  active  principle  of  hyoscyamus 
niger.  It  forms  a  yellowish  mass,  drying  with  difficulty;  has  an  odor  of 
tobacco,  and  a  sharp,  disagreeable  taste;  rather  soluble  in  water,  easily 
soluble  in  alcohol,  ether,  chloroform,  and  benzene. 

Duboisine  is  a  newly  discovered  alkaloid,  obtained  from  a  New 
Caledonian  plant,  whose  characters  appear  to  resemble  those  of  atropine. 


Alkaloids  from  Other  Sources. 

Colchicine,  C17H19NOB — from  Colchicum  autumnale.  Sulphuric  acid 
colors  it  yellow,  then  green.  Nitric  acid  colors  it  violet,  then  green. 
Sulphuric  acid,  containing  nitric  acid,  colors  it  violet,  turning  to  orange 
on  the  addition  of  an  alkali. 

Veratrine,  CMH6jlNa08 — from  Veratrum  album  and  V.  viride.  Cold 
sulphuric  acid  colors  it- first  yellow,  then  red,  and  finally  purple.  Bromine 
water  colors  it  violet,  violet-red.  Pure  boiling  hydrochloric  acid  colors 
it  red. 

Muscarine — from  Agaricus  muscarius. 

Physostigmine — Eserine— C16H21N3Oa — from  Physostigma  veneno- 
sum,  Calabar  bean.  Sulphuric  acid  colors  it  yellow,  passing,  after  a  time, 


300  GENERAL    MEDICAL    CHEMISTRY. 

to  red,  or  to  reddish  brown,  on  the  addition  of  bromine  water.  Hypo- 
chlorites  color  it  red  at  first;  the  color  is  discharged  by  an  excess  of  the 
reagent. 

Cocaine,  C17H04NO4 — from  HJrythroxylon  coca. 

Aconitine,  030"H47N07 — from  Aconitum  napellus.  When  dissolved  in 
aqueous  phosphoric  acid,  and  the  solution  carefully  evaporated  over  a 
small  flame,  it  produces  a  violet  color  at  a  certain  point  of  concentration. 
Dissolved  in  concentrated  sulphuric  acjjd  at  ordinary  temperatures,  the 
solution  is  at  first  yellow,  and  passes  very  slowly  through  brown  and  red- 
brown  to  violet. 

Pilocarpine — the  recently  discovered  alkaloid  of  jaborandi.  It  is  a 
crystalline  base,  forming  crystallizable  salts. 

Ptoamines — Septicine. — Under  these  names  substances  of  great  in- 
terest to  the  toxicologist  have  been  described  in  the  past  few  years;  they 
are  alkaloids  obtained  from  animal  tissues  in  complete  or  incipient  putre- 
faction. They  react  with  the  general  reagents  for  the  alkaloids;  some  are 
fixed,  others  volatile;  some  are  soluble  in  ether,  others  insoluble  in  ether, 
but  soluble  in  amyl  acohol;  others  insoluble  in  both  liquids;  some  are  strong 
reducing  agents  and  respond  to  the  iodic  acid  test  for  morphine.  They 
give  the  following  color  reactions,  which  may  appear  or  be  absent  accord- 
ing to  the  extent  to  which  the  putrefaction  has  progressed,  and  to  the 
method  of  extraction:  with  moderately  concentrated  sulphuric  acid  a 
violet-red  ;  the  same  color  with  hydrochloric  acid  containing  sulphuric 
acid  and  warmed;  with  sulphuric  acid  and  bromine  water  a  more  or  less 
distinct  red,  which  gradually  fades;  warmed  with  nitric  acid  and  afterward 
treated  with  potassium  hydrate,  a  golden-yellow;  with  iodic  acid,  sulphuric 
acid,  and  sodium  bicarbonate,  a  more  or  less  distinct  violet-red.  They  are 
readily  oxidizable,  turn  brown  on  contact  with  air,  and  give  off  odors 
resembling  those  of  urine  in  some  instances,  of  coniine  in  others,  and  of 
certain  flowers  in  others.  They  are  pungent  in  taste,  and  produce  a  sense 
of  numbness  in  the  tongue,  and  a  tickling  sensation  in  the  throat.  Of 
those  soluble  in  ether  or  in  amyl  alcohol,  some  are  non-poisonous,  and 
others  actively  toxic. 

Although  these  substances  present  such  striking  analogies  with  the 
vegetable  alkaloids,  they  differ  from  the  more  usually  employed  of  the  vege- 
table poisons  sufficientlv,  and  in  one  or  more  prominent  character  to  such 
an  extent,  that  any  fear  of  their  being  mistaken  for  a  vegetable  poison 
by  the  toxicologist  is  groundless. 


ALBUMINOIDS. 

PROTEIN  BODIES. 

The  substances  of  this  class,  exceedingly  complex  in  their  chemical 
composition,  are  the  organic  substances,  par  excellence,  being  never  absent 
in  living  vegetable  or  animal  cells,  to  whose  "  life  "  they  are  indispens- 
able. 

They  are  composed  of  carbon,  hydrogen,  oxygen,  nitrogen,  and  sul- 
phur; for  the  most  part  uncrystallizable,  and  prone  to  putrefaction.  They 
are,  with  some  notable  exceptions  (see  Peptones),  colloids,  and,  as  such, 
incapable  of  dialysis.  They  are  all,  when  dissolved,  Isevogyrous,  arid  for 
the  most  part  soluble  in  water. 

Although  the  individual  members  of  the  group  differ  from  each  other 


ALBUMINOIDS.  361 

considerably  in  their  characters,  they  have  many  properties  in  common. 
Thus,  they  respond  to  the  following  General  Tests :  1st.  Millons'  reagent  is 
made  by  dissolving,  by  the  aid  of  heat,  one  part  of  mercury  in  two  parts 
of  nitric  acid,  sp.  gr.  1.42;  after  solution  of  the  mercury,  the  liquid  is  di- 
luted with  twice  its  volume  of  water,  and,  after  standing  twenty-four 
hours,  decanted  from  the  deposit.  This  reagent,  added  to  a  solution  con- 
taining a  trace  of  an  albuminoid,  colors  it  purple-red  when  warmed  to 
about  70°.  3d,  Xanthoproteic  reaction. — Nitric  acid  colors  the  albuminoids 
yellow,  the  color  changing  to  orange  on  the  addition  of  ammonia.  3d. 
Pettenkofer's  reaction  is  produced  by  the  albuminoids  (see  p.  212).  4th. 
If  a  solid  albuminoid  be  touched  with  a  drop  of  cupric  sulphate  solution, 
and  then  with  a  drop  of  caustic  potassa  solution,  and  finally  washed,  a 
violet  mark  remains.  The  same  effect  is  produced  in  solutions  (see  p.  264). 
5th.  A  solution  of  an  albuminoid  in  excess  of  glacial  acetic  acid  is  colored 
violet,  and  rendered  faintly  fluorescent,  when  treated  with  concentrated 
sulphuric  acid.  6th.  Solutions  of  the  albuminoids  strongly  acidified  with 
acetic  acid  give  a  white  precipitate  with  potassium  ferrocyanide. 

Decompositions. — When  heated  with  dilute  acids  they  are  decom- 
posed into  two  substances:  one  insoluble,  amorphous,  yellowish,  called 
hemiprotein ;  the  other,  soluble  in  water,  insoluble  in  alcohol,  faintly 
acid,  called  hemialbumin.  A  prolonged  boiling  with  moderately  con- 
centrated sulphuric  acid  decomposes  the  albuminoids  into  well-defined 
bodies — leucin,  tyrosin;  aspartic,  and  glutamic  acids. 

Alkalies  dissolve  the  albuminoids  more  or  less  readily,  forming  soluble 
compounds  (see  below);  when  the  solution  is  boiled,  a  part  of  the  sulphur 
separates  in  the  form  of  sulphide  and  hyposulphite.  From  the  alkaline 
solution  a  substance  is  precipitated  by  acids,  which  is  Mulder's  protein, 
identical  with  albumin.  Concentrated  alkaline  solutions  decompose  them 
into  amido-acids.  By  fusion  with  alkalies,  alkaline  cyanides  are  also  pro- 
duced. The  action  of  caustic  baryta  upon  albuminoids  has  been  pro- 
ductive of  most  interesting  results  in  the  hands  of  Schiitzenberger. 
When  heated  with  caustic  baryta  and  water  to  100°,  carbonate,  sulphate, 
oxalate  and  phosphate  of  barium  are  deposited,  and  carbon  dioxide  and 
ammonia  given  off  in  the  same  proportions  as  would  result  if  urea  were 
similarly  treated;  upon  raising  the  temperature,  and  finally  heating,  under 
pressure,  at  200°,  a  crystalline  mass  is  obtained  which  contains  oxalic  and 
acetic  acids,  a  number  of  amido-acids,  aspartic  and  glutamic  acids,  and  a 
substance  resembling  dextrin. 

Heated  with  water,  under  pressure,  at  100°,  they  are  partly  dissolved 
and  partly  decomposed.  When  exposed  to  air  and  moisture  they  putrefy, 
with  formation  of  ammonia,  ammonium  sulphydrate,  carbon  dioxide,  vola- 
tile fatty  acids,  amido-acids  of  the  fatty  series,  lactic  acid,  indol  (?),  alka- 
loids. 

The  products  of  the  action  of  oxidizing  agents  upon  the  albuminoids 
vary  with  the  agent  used.  A  mixture  of  sulphuric  acid  and  manganese 
dioxide  or  potassium  dichromate,  produces  aldehydes  and  acids  of  the 
fatty  and  benzoic  series,  hydrocyanic  acid  and  cyanides.  Nitric  acid 
forms  xanthoproteic  acid  (see  above),  and,  afterward,  derived  acids  of  the 
benzoic  series.  Bromine  and  water  heated,  under  pressure,  with  albumi- 
noids, yield  carbon  dioxide,  oxalic  and  aspartic  acids,  amido-acids,  and  bro- 
mine derivatives  of  the  fatty  and  benzoic  series.  Potassium  permanganate 
produces  from  the  albuminoids  urea,  carbon  dioxide,  ammonia,  and  water. 

Constitution. — Although  our  knowledge  of  the  constitution  of  these 
complex  bodies  is  still  very  imperfect,  the  researches  of  Schtltzenberger 


362  GENERAL    MEDICAL    CHEMISTKY. 

and  others  render  it  probable  that  they  are  complex  amides,  related  to  the 
ureids  (q.  v.),  and  formed  by  the  combination  of  glycollamine,  leucine,  ty- 
rosine,  etc.,  with  oxygenated  radicals  of  the  acetic  and  benzoic  series. 

Classification. — In  the  present  state  of  our  knowledge,  the  only  classi- 
cation  of  these  substances  which  can  be  adopted  is  a  temporary  one, 
based  more  upon  the  physiological  relations  of  the  albuminoids  than  upon 
their  chemical  characters. 

I. — Soluble  in  pure  water,  coagulated'  l)y  heat.-^-The  members  of  this 
class  are  the  true  albumins  of  the  white  of  egg,  serum,  and  vegetable 
albumin. 

II. — Insoluble  in  pure  water,  soluble  in  water  without  alteration  in  the 
presence  of  neutral  salts,  alkalies,  and  acids,  and  capable  of  precipitation 
unchanged  from  these  solutions. 

1.  (jrlobulins. — Vitellin,  myosin,  paraglobulin,  fibrinogen. 

2.  Animal  caseins. — Milk  casein,  serum  casein. 

3.  Vegetable  caseins. — Gluten  casein,  legumin,  conglutin. 

4.  First  terms  of  decomposition  of  the  albuminoids  by  acids,  alkalies, 
and  soluble  ferments. — Albuminates  (so-called),  acid  albumin,  syntonin, 
hemiprotein,  peptones. 

III. — Insoluble  in  water  and  only  soluble  after  decomposition.  Can- 
not be  separated  without  alteration  from  their  solutions  in  acids  and 
alkalies. — Glutin-fibrin,  gliadin,  mucedin. 

IV. —  Coagulated  by  heat. — Coagulated  albumin  and  fibrin. 

V. — Amyloid  matter. — Lardacein. 

VI. —  Collagene  bodies. — Collagen,  elastin,  ossein  and  its  derivatives, 
chondrigen,  chondrin,  gelatin,  keratin. 

VII. — Mucilaginous  bodies. — Mucin,  paralbumin,  colloidin. 

I. — Egg  albumin  is  the  longest  known  of  the  albuminoids  and  ex- 
ists in  solution,  imprisoned  in  a  network  of  delicate  membranes,  in  the 
white  of  egg.  It  is  readily  obtained  in  an  impure  condition  by  cutting 
the  whites  of  eggs  with  scissors,  expressing  through  linen,  diluting  with 
an  equal  volume  of  water,  filtering  and  concentrating  the  filtrate  at  a 
temperature  below  +40°;  mineral  salts,  which  adhere  to  it  tenaciously, 
are  separated  by  dialysis.  It  seems  to  be  a  mixture  of  two  different  sub- 
stances, one  of  which  coagulates  at  63°,  and  has  the  rotary  power  [tfjj^ 
— 43°;  the  other  coagulates  at  74°,  and  has  the  value  of  [«]j  =  — 2o  . 

Its  solutions  are  not  precipitated  by  a  small  quantity  of  hydrochloric 
acid,  but  an  excess  of  that  acid  produces  a  deposit  which  is  difficultly 
soluble  in  hydrochloric  acid,  water,  and  salt  solution.  Its  characteristic 
reaction  is  that  it  is  coagulated  by  agitation  with  ether. 

Serum-albumin  exists  in  blood  serum,  chyle,  lymph,  pericardial 
fluid,  the  fluids  of  cysts  and  of  transudations,  in  milk  and,  pathologically, 
in  the  urine.  It  is  best  obtained  from  blood-serum,  after  removal  of 
paraglobulin  (q.  v.),  by  a  tedious  process,  and  only  then  in  a  state  of 
doubtful  purity.  It  is  less  abundant  in  the  blood  of  some  animals  than 
paraglobulin,  but  more  abundant  in  that  of  man. 

Solutions  of  serum-albumin  are  laevogyrous  Ja]j= — 56°;  they  are  not 
precipitated  by  carbon  dioxide,  by  acetic  or  orthophosphoric  acid,  by 
ether  or  by  magnesium  sulphate.  They  are  precipitated  by  mineral 
acids,  tannic  acid,  metaphosphoric  acid,  and  most  metallic  salts.  When 
heated  they  become  opalescent  at  60°,  and  coagulate  in  the  flocculent 
form  at  72°— 75°. 

Detection  and  determination  of  albumin  in  urine. — The  detection  of 
albumen  in  the  urine  can  be  effected  by  the  test  by  heat,  combined  with 


ALBUMINOIDS.  363 

that  by  nitric  acid.  The  clear  filtered  urine,  if  alkaline,  is  just  acidulated 
with  acetic  acid  and  then  heated  to  boiling;  if  albumin  be  present,  a 
cloudiness,  or  precipitate,  or  even  complete  solidification,  will  ensue,  and 
will  not  disappear,  but  rather  augment,  on  the  addition  of  concentrated 
nitric  acid.  Neither  test  alone  affords  conclusive  evidence  of  the  pres- 
ence of  albumin.  That  by  heat,  while  it  coagulates  albumin,  also  precipi- 
tates earthy  phosphates  if  they  be  present  in  excess;  but  these  are  dis- 
solved on  the  addition  of  nitric  acid.  Nitric  acid,  although  it  coagulates 
albumin  and  dissolves  the  phosphates,  precipitates  urates  if  present  in 
excess,  but,  on  the  other  hand,  the  urates  are  more  soluble  in  hot  than  in 
cold  solutions,  and,  consequently,  are  not  precipitated  by  heat. 

The  acidulation  of  the  alkaline  urine,  previous  to  heating',  is  impera- 
tive, as  such  urine  does  not  respond  to  the  heat-test  if  it  contain  a  small 
quantity  of  albumin,  unless  it  be  acidulated;  nitric  acid  should  not  be 
used  for  this  purpose,  nor  should  more  acetic  acid  be  added  than  just 
suffices  to  render  the  reaction  acid. 

The  only  chemical  method,  hitherto  devised,  of  determining  the  quan- 
tity of  albumin  in  urine  with  an  approach  to  accuracy,  is  gravimetric. 
Twenty  to  fifty  cubic  centimetres  of  the  filtered  urine,  according  as  the 
qualitative  testing  shows  albumin  to  be  present  in  large  or  small  quantity, 
and  diluted  with  water  if  the  amount  of  albumin  has  been  sufficient  to 
cause  solidification,  are  slowly  heated  over  the  water-bath,  and,  as  the 
boiling  temperature  is  approached,  three  to  four  drops  of  acetic  acid  are 
added;  after  the  urine  lias  been  at  100°  for  a  few  moments,  it  is  thrown 
upon  a  filter.  The  coagulum  is  washed  with  boiling  water,  then  with 
water  acidulated  with  nitric  acid,  then  with  alcohol,  and  finally,  with 
ether;  these  repeated  washings  not  only  remove  impurities,  but  cause 
the  coagulum  to  contract,  so  that  it  can  be  readily  detached  and  trans- 
ferred to  a  weighed  watch-glass;  upon  this  it  is  dried  at  115°  and  the 
whole  weighed. 

The  determination  of  albumen  by  the  polarimeter  or  by  volumetric 
methods  does  not  afford  satisfactory  results. 

Vegetable  albumin  exists  in  solution  in  all  vegetable  juices,  and 
forms  the  most  valuable  constituent  of  those  vegetables  which  are  used  as 
food.  It  is  coagulated  from  its  solutions  at  61° — 03°,  and  by  nearly  all  acids. 

II. — Vitelin  exists  in  the  yolk  of  egg  and  in  the  crystalline  lens.  It 
is  soluble  in  dilute  solution  of  sodium  chloride,  from  which  it  is  precipi- 
tated by  excess  of  water,  by  heating  to  75° — 80°,  and  by  alcohol.  It  is 
not  precipitated  by  solid  sodium  chloride.  It  dissolves  in  weak  alkaline 
solutions  without  alteration  and  in  very  dilute  hydrochloric  acid  (one  to 
one  thousand),  by  which  it  is  quickly  converted  into  syntonin. 

Myosin  is  one  of  the  principal  constituents  of  the  muscular  fibre  in 
rigor  mortis.  As  obtained  by  Kuhne  it  is  a  faintly  yellow,  opalescent, 
distinctly  alkaline  liquid,  which,  when  dropped  into  distilled  water,  de- 
posits the  myosin  in  globular  masses,  while  the  water  assumes  an  acid  re- 
action. It  is  insoluble  in  water,  easily  soluble  in  dilute  salt  solution, 
from  which  it  is  precipitated  by  the  addition  of  solid  sodium  chloride,  or 
by  a  heat  of  55° — 60°.  Very  dilute  hydrochloric  acid  dissolves  and  con- 
verts it  into  syntonin. 

Paraglobulin. — This  substance  has  been  described  by  various  authors 
under  the  names:  plasmine  (Denis),  serum  casein  (Panum),  serum  glo- 
buline,  fibrino-plastic  matter  (Schmidt),  serin  (Denis),  and  has  been  the 
subject  of  a  vast  amount  of  research. 

It  exists  in  blood-serum,  in  pericardial  fluid,  hydrocele   fluid,  lymph 


364 


GENERAL    MEDICAL    CHEMISTRY. 


and  chyle,  from  which  it  is  obtained  by  diluting  with  ten  to  fifteen  vol- 
umes of  ice-cold  water,  treatment  of  the  solution  with  a  strong1  current  of 
carbon  dioxide,  and  washing  the  collected  deposit  with  water  as  long  as  a 
portion  of  the  filtrate  precipitates  with  acetic  acid  and  potassium  ferro- 
cvanide,  or  with  silver  nitrate.  As  so  obtained  it  is  a  granular  substance, 
which  gradually  becomes  more  compact;  insoluble  in  water,  sparingly  sol- 
uble in  water  containing  car.bon  dioxide;  soluble  in  dilute  alkalies,  in 
lime-water,  in  solutions  of  neutral  alkaline  salts,  in  dilute  acids.  Its  so- 
lution in  very  dilute  alkaline  fluids  is  perfectly  neutral  and  is  not  coagu- 
lated by  heat,  except  after/am^  acidulation  with  acetic  or  mineral  acids; 
it  is  precipitated  by  a  large  volume  of  alcohol;  its  solutions  are  also 
precipitated  incompletely  by  dissolving  sodium  chloride  in  them  to  satura- 
tion, and  completely  by  similar  solution  of  magnesium  sulphate;  this  last 
method  of  precipitation  is  used  for  the  separation  of  paraglobulin  from 
serum-albumin  (see  Fibrin). 

Fibrinogen  ;  after  the  separation  of  paraglobulin  from  blood-plasma, 
as  described  above,  if  the  liquid  be  still  further  diluted  and  again  treated 
with  carbon  dioxide,  a  substance  is  obtained  which,  although  closely  re- 
sembling paraglobulin  in  many  characters,  is  distinct  from  it,  and,  unlike 
paraglobulin,  it  cannot  be  obtained  from  the  serum  separated  from  coagu- 
lated blood. 

Paraglobulin  and  fibrinogen  are  both  soluble  in  a  solution  of  sodium 
chloride  containing  five  to  eight  per  cent,  of  the  salt;  when  the  degree 
of  concentration  of  the  salt  solution  is  raised  to  twelve  to  sixteen  per 
cent.,  the  fibrinogen  is  precipitated,  while  the  paraglobulin  remains  in  so- 
lution and  is  only  precipitated,  and  then  incompletely,  when  the  percent- 
age of  salt  surpasses  twenty  (see  Fibrin). 

Milk  casein,  the  most  abundant  of  the  albuminoids  of  the  milk  of 
mammalians,  closely  resembles  alkali  albuminates,  with  which  it  is  proba- 
bly identical,  as  the  main  point  of  distinction  has  been  found  to  be  with- 
out significance;  unlike  pure  alkali  albuminates,  casein  is  coagulated 
from  its  solution  by  rennet  (the  product  of  the  fourth  stomach  of  the 
calf)  at  40°;  but  it  has  been  found  that  alkali  albuminate  is  also  so  co- 
agulated when  milk-sugar  and  fat  are  added  to  the  solution. 

Milk. — The  secretion  of  the  mammary  gland  is  water  holding  in  solu- 
tion casein,  albumin,  lactose,  and  salts,  and  fat  in  suspension.  Cream 
consists  of  the  greater  part  of  the  fat,  with  a  small  proportion  of  the 
other  constituents  of  the  milk.  Skim  milk  is  milk  from  which  the  cream 
has  been  removed.  Buttermilk  is  cream  from  which  the  greater  part  of 
the  fat  has  been  removed,  and  consequently  is  of  about  the  same  compo- 
sition as  skim  milk. 

The  composition  of  milk  differs  in  animals  of  different  species: 


Human. 

Cow. 

Goat. 

Sheep. 

ABS. 

Mare. 

Cream. 

Condens- 
ed milk. 

Water  

88.35 

84.28 

86.85 

83.30 

89.01 

90.45 

45.99 

25.68 

Solids  

11.65 

15.72 

13.52 

16.60 

10.99 

9.55 

54.01 

74.32 

Casein   .  .  . 
Albumin.  . 

(  3-15i 

3.57 

0.78 

2.53 
1.26 

\    5.73 

3.57 

2.53 

6.33 

16.83 

Fat  

3.87 

6.47 

4.34 

6.05 

1.85 

1.31 

43.97 

10.27 

Lactose  .  .  . 
Salts  

4.37 
0.26 

4.34 
0.63 

3.78 
0.65 

3.96 
0.68 

i    5.05 

j    5.43 
(    0.29 

3.28 
0.42 

44.33* 

2  80 

*  Including  28. 98  parts  of  cane-sugar. 


ALBUMINOIDS. 


365 


The  composition  of  cows'  milk  varies  considerably  according  to  the 
ag-e,  condition,  breed  and  food  of  the  cow;  to  the  time  and  frequency  of 
milking;  and  to  whether  the  sample  examined  is  from  the  first,  middle,  or 
last  part  of  each  milking. 

Cows'  milk  is  very  frequently  adulterated,  both  by  the  removal  of 
the  cream  and  the  addition  of  water.  For  ordinary  purposes,  the  purity 
of  the  milk  may  be  determined  by  observing  the  specific  gravity  and  the 
percentage  of  cream  by  t«he  lactometer  and  creamometer,  neither  of  which, 
used  alone,  affords  indications  which  can  be  relied  upon.  The  specific 
gravity  should  be  observed  at  the  temperature  for  which  the  instrument 
is  made,  as  in  a  complex  fluid  such  as  milk  no  valid  correction  for  tem- 
perature is  practical;  it  ranges  in  pure  milk  from  1027  to  1034,  it  being 
generally  the  lower  in  milk  which  has  been  watered,  and  in  such  as  is  very 
rich  in  cream,  and  the  higher  the  less  cream  is  present.  The  following 
table,  from  Hassall,  indicates  the  relations  between  specific  gravity  and 
percentage  of  cream: 


Specific  gravity  at  15.5°  .  . 

1034.5 

1029.7 

1030.4 

1031.3 

1032.1 

1027.5 

Cream  by  creamometer  .  .  . 

9.0 

7.5 

11.0 

9.0 

11.0 

20.5 

Specific  gravity  at  15.5°  .  . 

1031.2 

1028.8 

1030.3 

1032.3 

1029.9 

1030.6 

Cream  by  creamometer.  .  . 

21.0 

12.0 

15.3 

18.3 

13.2 

13.8 

Average  specific  gravity,  1030.7.      Average  per  cent,  of  cream,  13.5. 

The  percentage  of  cream  is  determined  by  the  creamometer:  a  glass 
tube  about  a  foot  long  and  half  an  inch  in  diameter,  the  upper  fifth  (ex- 
cluding about  an  inch  from  the  top)  being  graduated  into  hundredths  of  the 
whole,  the  0  being  at  the  top.  To  use  it,  it  is  simply  filled  to  the  0 
with  the  milk  to  be  tested,  sefr  aside  for  twenty  hours  and  the  point  of 
separation  between  milk  and  cream  read  off.  It  should  be  above  eight 
per  cent. 

This  method  of  determining  the  purity  of  milk,  although  sufficient 
for  ordinary  purposes,  should  not  be  considered  as  affording  evidence 
upon  which  to  base  legal  proceedings;  in  such  cases  nothing  short  of  a 
chemical  determination  of  the  percentage  of  fat,  and  of  solids  not  fat. 
should  be  accepted  as  evidence  of  the  impurity  of  milk. 

Serum-casein  is  a  substance  obtained  by  Kuhne  and  Eichwald  from 
blood-serum  diluted  with  ten  volumes  of  water,  freed  from  paraglobulin 
by  carbon  dioxide,  and  from  albumin  by  acetic  acid  and  heat.  It  is 
insoluble  in  salt  solutions,  slowly  soluble  in  a  one  per  cent,  solution  of 
sodium  hydrate.  Such  a  solution  is  partially  precipitated  by  carbon 
dioxide,  almost  completely  by  acetic  acid,  and  completely  by  heating  with 
excess  of  powdered  sodium  chloride;  incompletely  soluble  in  dilute  hydro- 
chloric acid. 

Gluten-casein. — That  portion  of  crude  gluten  (a  soft,  elastic,  grayish 
material  best  obtained  from  flour)  which  is  insoluble  in  alcohol,  hot  or 
cold;  tiegumin,  a  sparingly  soluble  albuminoid  obtained  from  peas, 
beans,  etc.;  and  Conglutin,  a  substance  closely  related  to  legumin  and  to 
gliadin,  but  differing  from  them  in  some  characters,  obtained  from  almonds, 
are  three  vegetable  albuminoids  resembling  casein. 

They  are  insoluble  in  pure  water,  readily  soluble  in  dilute  alkaline  so- 
lutions, from  which  they  are  precipitated  by  acids  and  by  rennet. 

Alkali  albuminates— proteins  of  Hoppe  Seyler — are  formed  when  an 


366  GENERAL   MEDICAL    CHEMISTRY. 

albuminoid  is  dissolved  in  concentrated  solutions  of  potassium  and  sodium 
hydrates;  it  is  very  probable  that  they  are  identical  with  serum  and  milk- 
casein. 

Acid  albumins  are  substances  obtained  by  precipitating  solutions  of 
albuminoids  by  the  simultaneous  addition  of  an  acid  and  a  large  quantity 
of  a  neutral  salt;  they  vary  exceedingly  in  composition  and  proper- 
ties. 

Syntonin,  parapeptone,  is  extracted  from  contractile  tissues;  the 
same  substance  is  formed  by  the  action  of  dilute  acids  upon  the  albumi- 
noids, and  as  the  first  product  of  the  action  of  the  gastric  juice,  or  of  mix- 
tures of  pepsin  and  dilute  sulphuric  acid  upon  albuminoids.  It  resembles 
serum  casein  closely,  the  only  divergence  in  their  properties  being  that 
syntonin  is  much  more  readily  soluble  in  a  0.1  per  cent,  solution  of  hydro- 
chloric acid,  and  in  faintly  alkaline  liquids. 

Peptones,  albuminose,  are  the  products  of  the  action  of  the  gastric 
and  pancreatic  juices  upon  albuminoids  during  the  process  of  digestion. 

They  are  soluble  in  water,  insoluble  in  alcohol  and  ether.  Their 
watery  solutions  are  neutral,  are  not  precipitated  by  acids  or  alkalies,  or 
by  heat  when  the  liquid  is  faintly  acid.  Alcohol  precipitates  them  in 
white,  casein-like  flocks,  which,  if  slowly  heated  to  90°  while  still  moist, 
form  a  transparent,  yellowish  liquid,  and,  on  cooling  of  the  liquid,  an 
opaque,  yellowish,  glassy  mass. 

The  most  important  character  of  the  peptones  is  that  they  differ  from 
other  albuminoids  in  being  capable  of  dialysis  through  animal  membranes. 
Their  presence  in  the  blood  has  not  been  demonstrated,  even  in  the  portal 
vein;  it  is  therefor  probable  that,  almost  immediately  after  their  entrance 
into  the  circulation,  they  are  reconverted  into  albuminoids  resembling, 
although  differing  from,  those  from  which  they  were  derived. 

IV. — Coagulated  albumins  are  obtained,  as  described  above,  from 
the  soluble  varieties  by  the  action  of  acids,  heat,  alcohol,  etc.  They  are 
insoluble  in  water,  alcohol,  solutions  of  neutral  salts,  dilute  hydrochloric 
acid;  difficultly  soluble  in  dilute  alkaline  solutions.  In  acetic  acid  they 
swell  up  and  dissolve  slowly;  from  this  solution  they  are  precipitated  by 
concentrated  salt  solution.  Concentrated  hydrochloric  acid  dissolves  them 
with  formation  of  syntonin.  By  the  action  of  gastric  juice,  natural  or 
artificial,  they  are  converted  first  into  syritonin,  then  into  peptones. 

Fibrin  is  obtained  when  blood  is  allowed  to  coagulate  or  is  whipped 
with  a  bundle  of  twigs.  When  pure  it  is  at  first  a  gelatinous  mass,  which 
contracts  to  a  white,  stringy,  tenacious  material,  made  up  of  numerous 
minute  fibrils;  when  dried  it  is  hard,  brittle,  and  hygroscopic.  It  is  in- 
soluble in  water,  alcohol,  ether;  in  dilute  acid  it  swells  up  and  dissolves 
slowly  and  incompletely.  When  heated  with  water  to  4-72°,  or  by  con- 
tact with  alcohol,  it  is  contracted,  and  is  no  longer  soluble  in  dilute  acids, 
but  soluble  in  dilute  alkalies.  In  solutions  of  many  neutral  salts  of  six  to 
ten  per  cent.,  it  swells  up  and  is  partially  dissolved;  from  this  solution 
it  separates  on  the  addition  of  water,  or  upon  the  application  of  heat  to 
+  73°,  or  by  acetic  acid  or  alcohol.  Moist  fibrin  has  the  curious  property 
of  decomposing  oxygenated  water  with  copious  evolution  of  oxygen. 

Fibrin  does  not  exist  as  such  in  the  blood,  and  the  method  of  its  form- 
ation and  of  the  clotting  of  blood  has  been  the  subject  of  a  vast  amount 
of  experiment  and  argument;  nor  can  the  question  be  said  to  be  definitely 
set  at  rest.  In  the  light  of  the  researches  of  Denis,  Schmidt,  and  espe- 
cially of  Hammarsten,  it  may  be  considered  as  almost  proven  that  fibrin  is 
formed  from  fibrinogen  under  favorable  circumstances,  and  by  a  transfer- 


ALBUMINOIDS.  3G7 

mation  which  is  not  yet  understood.     Whether  paraglobulin  plays  any 
part  directly  in  the  formation  of  fibrin  orvnot,  is  still  an  open  question. 

V.  Amyloid  is  a  pathological  product,  occurring  in  fine  grains,  re- 
sembling starch-granules  in  appearance,  in  the  membranes  of  the  brain 
and  cord,  in  waxv  and  lardaceous  liver,  and  in  the  walls  of  the  blood-ves- 
sels.    Its  composition  is  that  of  the  albuminoids,  from  which  it  differs  in 
being  colored  red  by  iodine;  violet  or  blue  by  iodine  and  sulphuric  acid. 
Soluble  in  hydrochloric  acid  with  formation  of  syntonin;  and  in  alkalies. 
It  is  not  attacked  by  the  gastric  juice,  and  is  not  as  prone  to  putrefaction 
as  the  albuminoids. 

VI.  Collagen. — Bony  tissue  is  made  up  mainly  of  tricalcic  phosphate, 
combined  with  an  organic  material  called  ossein,  which  is  a  mixture   of 
collagen,  elastin,  and  an  albuminoid  existing  in  the  bone-cells.     Collagen 
also  exists  in  all  substances  which,  when  treated  with  water  under  the  in- 
fluence of  heat  and  pressure,  yield  gelatin.     It  is  insoluble  in  cold  water, 
but  by  prolonged  boiling  is  converted  into  gelatin,  which  dissolves.     It 
is  dissolved  by  alkalies. 

Gelatin,  obtained  as  above,  from  ossein,  exists  in  the  commercial  pro- 
duct of  that  name,  and  in  a  less  pure  form  in  glue.  When  pure  it  is  an 
amorphous,  translucent,  yellowish,  tasteless  substance,  which  swells  up  in 
cold  water,  without  dissolving,  and  forms,  with  boiling  water,  a  thick, 
sticky  solution,  which  on  cooling  becomes,  according  to  its  concentration,  a 
hard  glassy  mass  or  a  soft  jelly — the  latter,  even  when  the  solution  is  very 
dilute.  It  is  insoluble  in  alcohol  and  ether,  but  soluble,  on  warming, 
in  glycerin;  the  solution  in  the  last-named  liquid  forms,  on  cooling,  a 
jelly  which  has  recently  been  applied  to  various  contrivances  for  copying 
writing.  A  film  of  gelatin  impregnated  with  potassium  dichromate  be- 
comes hard  and  insoluble  on  exposure  to  sunlight — a  property  which  has 
been  utilized  in  photography. 

Elastin  is  obtained  from  elastic  tissues  by  successive  treatment  with 
boiling  alcohol,  ether,  water,  concentrated  acetic  acid,  dilute  potash  solu- 
tion and  water.  It  is  fibrous,  yellowish;  swells  up  in  water  and  becomes 
elastic;  soluble  with  a  brown  color  in  concentrated  potash  solution.  It 
contains  no  sulphur,  and  on  boiling  with  sulphuric  acid  yields  glycocol. 

Chondrigen,  a  substance  closely  resembling  collagen,  existing  in  the 
cartilage  and  the  tissues  of  lower  animals,  which  differs  from  collagen  in 
yielding  chondrin  when  heated  with  water,  under  pressure. 

Chondrin  is  distinguished  from  gelatin  by  being  precipitated  by  al- 
most all  acids,  including  acetic;  in  not  precipitating  with  tannin;  and  in 
yielding  leucin  in  place  of  glycocol  on  boiling  with  sulphuric  acid. 

Keratin  is  the  organic  basis  of  horny  tissues,  hair,  nails,  feathers, 
whalebone,  epithelium,  tortoise-shell,  etc.  It  is  probably  not  a  distinct 
chemical  compound,  but  a  mixture  of  several  closely  related  bodies. 

IVEucin  is  a  substance  resembling  the  albuminoids,  but  containing  no 
sulphur  and  existing  in  the  different  varieties  of  mucus,  in  certain  patho- 
logical fluids,  in  the  bodies  of  molluscs,  in  the  saliva,  bile,  etc.  Its 
solutions,  like  the  fluids  in  which  it  occurs,  are  viscid.  It  is  precipi- 
tated by  acetic  acid  and  by  nitric  acid,  but  is  dissolved  by  an  excess  of 
the  latter;  it  dissolves  readily  in  alkaline  solutions,  and  swells  up  in 
water,  with  which  it  forms  a  false  solution.  It  is  not  coagulated  by  heat. 


368  GENERAL    MEDICAL    CHEMISTRY. 


SOLUBLE  ANIMAL  FERMENTS. 

Under  this  head  are  classed  substances  which  are  closely  related  to 
the  albuminoids,  which  exist  in  animal  fluids,  and  which  have  the  power 
of  effecting  peculiar  changes,  jn  other  organic  substances.  Prominent 
among  them  are  ptyalin,  pepsin," &nd  pantweatin. 

Ptyalin  is  a  substance  closely  resembling  diastase  in  its  characters 
and  properties,  existing  in  saliva.  Like  diastase,  it  converts  starch  into 
sugar. 

Pepsin  is  the  albuminoid  ferment  of  the  gastric  juice.  Attempts 
to  separate  it  without  admixture  of  other  substances  have  hitherto  proved 
fruitless;  nevertheless,  mixtures  containing  it  and  exhibiting  its  charac- 
teristic properties  more  or  less  actively,  have  been  obtained  by  various 
methods.  The  most  simple  is  that  of  Wittich,  which  consists  in  macera- 
ting the  finely  divided  mucous  membrane  of  the  stomach  in  alcohol  for 
forty-eight  hours,  and  afterward  extracting  it  with  glvcerin;  this  forms 
a  solution  of  pepsin,  which  is  quite  active  and  resists  putrefaction  well, 
and  from  which  a  substance  containing  the  pepsin  is  precipitated  by  a 
mixture  of  alcohol  and  ether. 

If  pepsin  is  required  in  the  solid  form,  it  is  best  obtained  by  Briicke's 
method.  The  mucous  membrane  of  the  stomach  of  the  pig  is  cleaned  and 
detached  from  the  muscular  coat  by  scraping;  the  pulp  so  obtained  is  di- 
gested with  dilute  phosphoric  acid  at  38°,  until  the  greater  part  of  it  is 
dissolved  ;  the  filtered  solution  is  neutralized  with  lime-water;  the  pre- 
cipitate is  collected,  washed  with  water,  and  dissolved  in  dilute  hydro- 
chloric acid  ;  to  this  solution  a  saturated  solution  of  cholesterin,  in  a 
mixture  of  four  parts  alcohol  and  one  part  ether,  is  gradually  added  ; 
the  deposit  so  formed  is  repeatedly  shaken  with  the  liquid,  collected  on  a 
filter,  washed  with  water  and  then  with  dilute  acetic  acid,  until  all  hydro- 
chloric acid  is  removed;  it  is  then  treated  with  ether  and  water:  the  former 
dissolves  cholesterin  and  is  poured  off,  the  latter  the  pepsin;  after  several 
shakings  with  ether  the  aqueous  liquid  is  evaporated  at  38°,  when  it 
leaves  the  pepsin  as  an  amorphous,  grayish  white  substance;  almost  in- 
soluble in  pure  water,  readily  soluble  in  acidulated  water,  probably  form- 
ing a  compound  with  the  acid,  which  possesses  the  property  of  converting 
albuminoids  into  peptones. 

The  so-called  pepsina  porci  is  either  the  calcium  precipitate  obtained 
as  described  in  the  first  part  of  the  above  method;  or,  more  commonly, 
the  mucous  membrane  of  the  stomach  of  the  pig,  scraped  off,  dried,  and 
mixed  with  rice-starch. 

Pancreatin. — Under  this  name,  substances  obtained  from  the  pancrea- 
tic secretion,  and  from  extracts  of  the  organ  itself,  have  been  described, 
and  to  some  extent  used  therapeutically.  They  do  not,  however,  con- 
tain all  the  ferments  of  the  pancreatic  juice,  and  in  many  instances  are 
inert  albuminoids.  The  actions  of  the  pancreatic  juice  are  various:  1st, 
it  rapidly  converts  starch,  raw  or  hydrated,  into  sugar;  2d,  in  alkaline 
solution — its  natural  reaction — it  converts  albuminoids  into  peptones;  3d, 
it  emulsifies  neutral  fats;  4th,  it  decomposes  fats,  with  absorption  of 
water  and  liberation  of  glycerin  and  fatty  acids. 

The  pancreatic  secretion  probably  contains  a  number  of  ferments — 
certainly  two,  probably  three.  The  one  of  these  to  which  it  owes  its  pep- 
tone-forming power  has  been  obtained  in  a  condition  of  comparative 


ANIMAL    COLORING    MATTERS.  369 

purity  by  Ktihne,   and   called  by  him  trypsin  •  in   aqueous  solution  it 
digests  fibrin  almost  immediately,  but  it  exerts  no  action  upon  starch. 

The  diastatic  (sugar-forming)  ferment  of  the  pancreatic  juice  has  not 
been  separated,  although  a  glycerin  extract  of  the  finely  divided  pancrea- 
tic tissue  contains  it,  along  with  trypsin. 


ANIMAL   COLORING  MATTERS. 

Haemoglobin  and  its  derivatives.  —  Hcemato-crystallin.  —  The 
coloring  matter  of  the  blood  is  a  highly  complex  substance,  resembling 
the  albuminoids  in  many  of  its  properties,  but  differing  from  them  in 
being  crystallizable  and  in  containing  iron. 

It  exists  in  the  red  corpuscles,  from  which  it  is  obtained  by  the  follow- 
ing method:  the  blood  is  allowed  to  coagulate  in  a  capsule  and  to  remain 
at  rest  for  twenty-four  hours;  the  serum  is  decanted,  the  clot  washed  with 
water,  cut  into  small  pieces,  and  these  again  washed  until  the  washings 
are  not  strongly  precipitated  by  mercuric  chloride;  the  clot  is  then  ex- 
tracted with  water  at  30° — 40°,  and  the  liquid  filtered  and  collected  in  a 
cylinder  surrounded  with  ice.  A  known  fraction  of  the  solution  is 
treated  with  alcohol,  gradually  added  from  a  burette  during  constant 
stirring  of  the  solution,  until  a  slight  precipitate  is  formed;  to  the  re- 
mainder of  the  aqueous  liquid  a  somewhat  smaller  proportion  of  alcohol 
is  then  added  than  is  required  to  form  a  precipitate;  the  mixture  is  placed 
in  a  freezing  mixture,  where,  after  some  hours,  an  abundant  crop  of 
crystals  separates;  this  is  collected  on  a  filter,  washed  first  with  water 
containing  alcohol,  and  then  with  iced  water,  and  finally  dried  below  0°. 

Haemoglobin  exists  in  two  conditions  of  oxidation;  in  the  form  in 
which  it  exists  in  arterial  blood,  and  as  obtained  above,  it  is  loosely  com- 
bined with  a  certain  quantity  of  oxygen,  and  is  known  as  oxyhcemoglobin. 
The  mean  of  many  nearly  concording  analyses  shows  its  composition  to  be 
C600H960N154FeS30J79.  When  obtained  from  the  blood  of  man  and  from 
that  of  many  of  the  lower  animals,  it  crystallizes  in  beautiful  red  prisms 
or  rhombic  plates;  that  from  the  blood  of  the  squirrel  in  hexagonal  plates; 
and  that  from  the  guinea-pig  in  tetrahedra.  The  crystals  are  always 
doubly  refracting.  It  may  be  dried  in  vacuo  at  0°;  when  it  contains 
three  to  four  per  cent,  of  water  of  crystallization,  which  it  loses  at  110° — 
120°;  if  thoroughly  dried  below  0°,  it  may  be  heated  to  100°  without  de- 
composition, but  the  presence  of  a  trace  of  moisture  causes  its  decompo- 
sition at  a  much  lower  temperature.  Its  solubility  in  water  varies  with  the 
species  of  animal  from  whose  blood  it  was  obtained;  thus,  that  from  the 
guinea-pig  is  but  sparingly  soluble,  while  that  from  the  pig  is  very  solu- 
ble in  water.  It  is  also  dissolved  unchanged  by  very  weak  alkaline  solu- 
tions, but  is  decomposed  by  acids  or  salts  having  an  acid  reaction. 

Il&moglobin,  or  reduced  haemoglobin,  is  formed  from  oxyhsemoglo- 
bin  in  the  economy  during  the  passage  of  arterial  into  venous  blood,  and 
by  the  action  of  reducing  agents,  or  by  boiling  its  solution  at  40°  in  the 
vacuum  of  the  mercury  pump. 

Oxyhaemoglobin  is  of  a  much  brighter  color  than  the  reduced,  and 
has  a  different  absorption  spectrum.  The  spectrum  of  oxyhsernoglobin 
has  two  bands  between  D  and  E;  the  one  nearer  D  being  the  narrower, 
darker,  and  more  sharply  defined  of  the  two,  it  is  also  the  last  to  disap- 
pear on  dilution;  beyond  a  certain  degree  of  concentration  of  the  solu- 
tion the  two  bands  unite  together,  forming  a  single,  broad,  dark  band, 
24 


370  GENERAL   MEDICAL    CHEMISTRY. 

extending*  beyond  both  D  and  E.  The  spectrum  of  haemoglobin,  on  the 
other  hand,  has  but  one  band,  much  broader  and  fainter  than  either  of 
the  oxyhaemoglobin  bands,  extending  from  D  to  about  as  near  E  as  the 
border  of  the  oxyhaemoglobin  band  nearest  that  line. 

Haemoglobin,  in  contact  with  oxygen  or  air,  is  immediately  con- 
verted into  oxyhaemoglobin.  With  carbon  monoxide  it  forms  a  com- 
pound resembling  oxyhsemoglobin  in  the  color  of  its'  solution,  but  in 
which  the  carbon  dioxide  cannot  be  replaced  by  oxygen  ;  for  which 
reason  haemoglobin,  once  combined  with  carbon  monoxide,  becomes  per- 
manently-unfit to  fulfil  its  function  in  respiration.  The  spectrum  of  the 
carbon  monoxide  compound  resembles  somewhat  that  of  oxyhaemoglobin, 
except  that  the  bands  are  more  nearly  equal  in  width  and  intensity,  and 
are  rather  nearer  the  violet  end  of  the  spectrum. 

When  a  solution  of  oxyhaemoglobin  is  boiled,  it  becomes  turbid,  and 
a  dirty,  brownish  red  coagulum  is  deposited;  the  haemoglobin  has  been  de- 
composed into  an  albuminoid  (or  mixture  of  albuminoids),  called  by  Preyer 
globin,  &nd  hcematin.  The  latter,  atone  time  supposed  to  be  the  blood-color- 
ing matter,  is  a  blue-black  substance,  having  a  metallic  lustre  and  incapa- 
ble of  crystallization;  it  is  insoluble  in  water,  alcohol,  ether,  and  dilute 
acids;  soluble  in  alkaline  solutions.  It  has  the  composition  C68H70N8FeaOlo 
(?).  Although  itself  uncrystallizable,  hsematin  combines  with  hydro- 
chloric acid  to  form  a  compound  which  crystallizes  in  rhombic  prisms, 
and  which  is  identical  with  the  earliest  known  crystalline  blood-pigment, 
/UJBmin,  or  Teichmann's  crystals. 

When  reduced  hsematin  is  decomposed  as  above,  in  the  absence  of 
oxygen,  hsematin  is  not  produced,  but  a  substance  identical  with  that 
called  reduced  hce  mat  in,  and  called  by  Hoppe-Seyler  hcemocromogen. 

Biliary  pigments. — There  are  certainly  four,  and  probably  more, 
pigmentary  bodies  obtainable  from  the  bile  and  from  biliary  calculi, 
some  of  which  consist  in  great  part  of  them. 

Bilirubin,  C32H36N4O6,  is,  when  amorphous,  an  orange-yellow  powder, 
and  when  crystalline,  in  red  rhombic  prisms.  It  is  sparingly  soluble  in 
water,  alcohol,  and  ether  ;  readily  soluble  in  hot  chloroform,  carbon  di- 
sulphide,  benzene,  and  in  alkaline  solutions.  When  treated  with  nitric 
acid  containing  nitrous  acid,  or  with  a  mixture  of  concentrated  nitric 
and  sulphuric  acids,  it  turns  first  green,  then  blue,  then  violet,  then  red, 
and  finally  yellow.  This  reaction,  known  as  Gmelin's,  is  very  delicate, 
and  is  used  for  the  detection  of  bile-pigments  in  icteric  urine  and  in  other 
£uids. 

Hiliverdin,  C32H36N4O8,  is  a  green  powder,  insoluble  in  water,  ether, 
and  chloroform;  soluble  in  alcohol  and  in  alkaline  solutions.  It  exists  in 
green  biles,  but  its  presence  in  yellow  biles  or  biliary  calculi  is  doubtful. 
It  responds  to  Gmelin's  test.  In  alkaline  solution  it  is  changed  after  a 
time  into  biliprasin. 

Bilifuscin,  C18H20N2O4 — obtained  in  small  quantity  from  human  gall- 
stones, is  an  almost  black  substance,  sparingly  soluble  in  water,  ether,  and 
chloroform;  readily  soluble  in  alcohol  and  in  dilute  alkaline  solutions. 
Its  existence  in  the  bile  is  doubtful. 

JJiliprasin,  C10H22N2O6  (?),  exists  in  human  gall-stones,  in  ox-gall, 
and  in  icteric  urine.  It  is  a  black,  shining  substance,  insoluble  in  water, 
ether,  and  chloroform;  soluble  in  alcohol  and  in  alkaline  solutions. 

Urobilin,  or  hydrobttirubin,  C32H40N4O7.  Under  the  name  urobilin, 
Jaffe  described  a  substance  which  he  obtained  from  dark,  febrile  urine, 
and  which  he  regarded  as  the  normal  coloring  matter  of  that  fluid;  subse- 


ANIMAL    COLORING    MATTERS.  371 

quently  he  obtained  it  from  dog's  bile  and  from  human  bile,  from  gall- 
stones and  from  fieces.  Stercobilin  from  the  faeces  is  identical  with  uro- 
bilin. 

Urinary  pigments. — Our  knowledge  of  the  nature  of  the  substances 
to  which  the  normal  urinary  secretion  owes  its  color  is  exceedingly  un- 
satisfactory. Jaffe  in  his  discovery  of  urobilin  shed  but  a  transient  light 
upon  the  question,  as  that  substance  has  been  found  to  exist  in  but  a 
small  percentage  of  the  normal  urines  examined,  although  they  certainly 
contain  a  substance  readily  convertible  into  it  ;  a  great  deal  of  confusion 
has  also  been  introduced  into  the  subject  by  the  description,  especially 
by  Thudichum,  of  ill-defined  mixtures  as  urinary  pigments.  Besides  the 
substance  convertible  into  urobilin,  and  sometimes  urobilin  itself,  human 
and  mammalian  urines  contain  at  least  one  other  pigmentary  body: 
uroxanthin,  or  indigogen.  This  substance  was  formerly  considered  as 
identical  with  indlcan,  a  glucoside  existing  in  plants  of  the  genus  Isatis, 
which,  when  decomposed,  yields,  among  other  substances,  indigo-blue. 
Uroxanthin,  however,  differs  from  indican  in  that  the  former  is  not  de- 
composed by  boiling  with  alkalies,  and  does  not  yield  any  glucose-like 
substance  on  decomposition  ;  the  latter  is  almost  immediately  decom- 
posed by  boiling  alkaline  solutions,  and,  under  the  influence  of  acids  and 
of  certain  ferments,  yields,  besides  indigo  blue,  indiglucin,  a  sweet,  non- 
fermentable  substance,  which  reduces  Fehling's  solution. 

Uroxanthin  is  a  normal  constituent  of  human  urine,  but  is  much  in- 
creased in  the  first  stage  of  cholera,  in  cases  of  cancer  of  the  liver, 
Addison's  disease,  and  intestinal  obstruction.  It  has  also  been  detected 
in  the  perspiration. 

The  presence  of  uroxanthin  in  the  urine  is  indicated  by  the  following 
tests:  1st,  ten  cubic  centimetres  of  the  urine  are  treated  with  an  equal 
volume  of  hydrochloric  acid,  and  then  with  a  saturated  solution  of  chloride 
of  lime,  added  guttatim;  the  solution  is  colored,  according  to  the  amount 
of  uroxanthin  present,  red,  violet,  green,  or  blue;  on  being  filtered  it 
leaves  a  blue  deposit  on  the  paper;  2d,  three  or  four  cubic  centimetres 
of  concentrated  hydrochloric  acid  are  placed  in  a  test-tube,  and  thirty  to 
forty  drops  of  urine  added;  it  assumes  a  red,  violet,  or  blue  color;  3d,  the 
urine  is  warmed  with  two  parts  of  nitric  acid  to  60° — 70°,  and  shaken 
with  chloroform;  the  latter  fluid  is  colored  violet-blue,  and,  if  examined 
by  the  spectroscope,  shows  an  absorption-band  between  C  and  D. 

Melanin  is  the  black  pigment  of  the  choroid,  melanotic  tumors,  skin 
of  the  negro;  and  occurs  pathologically  in  the  urine,  and  deposited  in  the 
air-passages. 


372  GENERAJL    MEDICAL    CHEMISTRY. 


SILICON. 
Si 28 

Also  known  as  silicium,  resembles  carbon,  and  occurs  in  three  allo- 
tropic  forms:  Amorphous  silicon,  formed  when  silicon  chloride  is  passed 
over  heated  potassium  or  sodium,  is  a  dark  brown  powder,  heavier  than 
water;  when  heated  in  air  it  burns  with  a  bright  flame  to  the  dioxide. 
It  dissolves  in  potash  and  in  hydrofluoric  acid,  but  is  not  attacked  by 
other  acids.  Graphitoid  silicon  is  obtained  by  fusing  potassium  fluosili- 
cate  with  aluminium.  It  forms  hexagonal  plates,  of  sp.  gr.  2.49,  which 
do  not  burn  when  heated  to  whiteness  in  oxygen,  but  may  be  oxidized  at 
that  temperature  by  a  mixture  of  potassium  chlorate  and  nitrate.  It  dis- 
solves slowly  in  alkaline  solutions,  but  not  in  acids.  Crystallized  silicon, 
corresponding  to  the  diamond,  forms  crystalline  needles,  which  are  only 
attacked  by  a  mixture  of  nitric  and  hydrofluoric  acids. 

Silicon,  although  closely  related  to  carbon,  exists  in  nature  in  but  few 
compounds;  it  has  been  caused  to  form  artificial  combinations,  however, 
which  indicate  its  possible  capacity  to  exist  in  substances  corresponding 
to  those  carbon  compounds  vulgarly  known  as  organic,  e.g.,  silicichloro- 
form,  and  silicibromoform,  SiHCl3  and  SiHBr3. 

Hydrogen  silicide,  SiH4 — is  obtained  as  a  colorless,  insoluble,  spon- 
taneously inflammable  gas,  by  passing  the  current  of  a  galvanic  battery 
of  twelve  cells  through  a  solution  of  common  salt,  using  a  plate  of  alu- 
minium, alloyed  with  silicon,  as  the  positive  electrode. 

Silicon  chloride,  SiCl4 — a  colorless,  volatile  liquid,  having  an  irri- 
tating odor;  sp.  gr.  1.52;  boils  at  59°;  formed  when  silicon  is  heated  to 
redness  in  chlorine. 

Silicic  oxide — Silicic  anhydride — Silex — SiO2 — is  the  most  impor- 
tant of  the  compounds  of  silicon.  It  exists  in  nature  in  the  different 
varieties  of  quartz,  and  in  the  rocks  and  sands  containing  that  mineral, 
in  agate,  carnelian,  flint,  etc.  Its  purest  native  form  is  rock  crystal;  its 
hydrates  occur  in  the  opal,  and  in  solution  in  natural  waters.  When  crys- 
tallized it  is  fusible  with  difficulty;  when  heated  to  redness  with  the  al- 
kaline carbonates  it  forms  silicates,  which  solidify  to  glass-like  masses  on 
cooling.  It  unites  with  water* to  form  a  number  of  acid  hydrates.  The 
normal  hydrate,  SiO4H4,  has  not  been  isolated,  although  it  probably  exists 
in  the  solution  obtained  by  adding  an  excess  of  hydrochloric  acid  to  a 
solution  of  sodium  silicate.  A  gelatinous  hydrate,  soluble  in  water  and 
in  acids  and  alkalies,  is  obtained  by  adding  a  small  quantity  of  hydro- 
chloric acid  to  a  concentrated  solution  of  sodium  silicate. 

Hydrofluosilicic  acid,  SiF6H2 — is  obtained  in  solution  by  passing 
the  gas  disengaged  by  gently  heating  a  mixture  of  equal  parts  of  fluor- 
spar and  pounded  glass,  and  six  parts  of  sulphuric  acid,  through  water, 
the  disengagement  tube  being  protected  from  moisture  by  a  layer  of 
mercury.  It  is  used  in  analysis  as  a  test  for  potassium  and  sodium. 


MOLYBDENUM.  373 

VII.     MOLYBDENUM  GROUP. 
MOLYBDENUM,  Mo,  96;  TUNGSTEN,  W,  184;  OSMIUM,  Os,  200. 

The  position  of  this  group  is  doubtful;  osmium  forms  an  oxide  which 
is  basic  in  character,  and  also  exists  in  a  sulphite,  and  it  consequently  be- 
longs to  the  next  class;  nevertheless,  the  relations  of  its  compounds  to 
those  of  tungsten  and  molybdenum  are  such  as  to  induce  us  to  place  it  in 
the  same  group  with  them.  It  is  probable  that  the  lower  oxides  of  tung- 
sten and  molybdenum  will  be  found  to  possess  basic  characters,  in  which 
case  the  entire  group  should  be  transferred  to  the  following  class. 

Molybdenum — isolated  with  difficulty  by  reduction  of  its  oxides, 
which  are  obtained  from  a  native  sulphide. 

Molybdic  anhydride,  Mo03 — unites  with  water  to  form  a  number  of 
acids,  the  ammonium  salt  of  one  of  which  is  a  sensitive  reagent  for  phos- 
phoric acid.  The  conjugate  phosphomolybdic  acid  is  a  valuable  reagent 
for  the  alkaloids. 

Tungsten—  Wolfram— occurs  associated  with  tin. 

Tungstic  anhydride,  W03 — a  yellow  powder  which  unites  with  water 
to  form  several  acid  hydrates,  one  of  which,  metatungstic  acid,  W403H2, 
is  used  as  a  test  for  alkaloids,  as  are  also  the  conjugate  silico-tungstic  and 
phospho-tungstic  acids.  Sodium  tungstate  is  used  to  render  fabrics  non- 
inflammable. 

Osmium  is  a  rare  element  occurring  with  iridium  in  platinum  ores. 
The  oxide,  OsO1?  known  as  osmic  acid,  is  used  as  a  staining  agent  in 
histological  laboratories.  Its  vapor  is  intensely  irritating. 


8T4  GENERAL    MEDICAL    CHEMISTRY. 


CLASS  HI. 

ELEMENTS  WHOSE  OXIDES  UNJTE  WITH  WATER,  SOME  TO  FORM  BASES, 

OTHERS    TO    FORM   AdDS.       WflflCH    FORM    OxYSALTS. 

I.     GOLD  GROUP. 
GOLD Au 197 

This,  the  only  member  of  the  group,  forms  two  series  of  compounds: 
in  one,  AuCl,  it  is  univalent;  in  the  other,  AuCl3,  trivalent.  Its  hydrate, 
auric  acid,  Au  (OH)a,  corresponds  to  the  oxide  Au203.  Its  oxysalts  are 
unstable. 

It  is  yellow  or  red  by  reflected  light,  green  by  transmitted  light,  red- 
dish purple  when  finely  divided;  not  very  tenacious;  very  malleable  and 
ductile;  softer  than  silver;  fuses  at  about  1200°;  sp.gr.  19.258  when  cast, 
19.367  when  hammered. 

It  is  not  acted  upon  by  water,  air,  oxygen,  or  single  mineral  acids. 
It  combines  directly  with  chlorine,  bromine,  iodine,  phosphorus,  anti- 
mony, arsenic,  and  mercury.  It  dissolves  in  nitro-muriatic  acid.  It  is 
oxidized  on  contact  of  air  by  alkalies  in  fusion. 

Aurous  chloride,  AuCl — a  pale  yellow,  insoluble  powder  formed 
when  auric  chloride  is  heated  to  200°;  decomposed  at  higher  tempera- 
tures into  chlorine  and  gold. 

Auric  chloride — Gold  trichloride — AuCls — obtained  by  dissolving 
gold  in  aqua  regia,  evaporating  at  about  100°,  and  purifying  by  crystal- 
lization from  water.  Deliquescent  yellow  prisms,  very  soluble  in  water, 
alcohol,  and  ether.  Readily  decomposed,  with  separation  of  gold,  on  con- 
tact with  phosphorus  or  with  reducing  agents.  Its  solution,  treated  with 
the  chlorides  of  tin,  deposits  the  flocculent  purple  of  Cassius.  With 
the  alkaline  chlorides  it  forms  permanent  double  chlorides — chloraurates. 
It  stains  the  skin  purple. 

Sodium  chloraurate  and  aurous  iodide  have  been  used  medicinally. 
The  trichloride  is  an  active  poison  and  a  corrosive,  being  decomposed  by 
organic  matter  with  deposition  of  gold  and  liberation  of  chlorine. 

Analytical  characters. — Hydrogen  sulphide — from  neutral  or  acid 
solution;  blackish  brown  precipitate  in  the  cold;  insoluble  in  nitric  and 
hydrochloric  acids,  soluble  in  aqua  regia  and  in  yellow  ammonium  sulphy- 
drate.  Stannous  chloride,  with  a  little  chlorine  water,  purple-red  pre- 
cipitate, insoluble  in  hydrochloric  acid.  Ferrous  sulphate,  brown  de- 
posit, which  assumes  the  lustre  of  gold  when  dried  and  burnished. 


II.     IRON  GROUP. 
CHROMIUM,  CR,  52.4;  MANGANESE,  MN,  55.2;  IRON,  FE,  56. 

These  elements  form  two  series  of  compounds;  in  one  a  single  atom 
is  divalent,  as  in  Fe"Cl0;  in  the  other,  two  atoms  combined  form  a  hexava- 
lent  group,  as  in  (Fe)viClfi.  The  oxides  M03  are  anhydrides,  correspond- 
ing to  which  are  acids  and  salts. 


CHROMIUM.  375 


CHROMIUM. 
Cr 52.4 

The  element  is  isolated  with  difficulty  from  its  oxide  or  chloride.  It 
is  steel-gray,  hard,  brilliant,  magnetic  at  low  temperatures;  sp.  gr.  6.8  at 
20°.  It  combines  with  oxygen  only  at  a  red  heat;  is  not  attacked  by 
acids,  except  hydrochloric  acid;  is  readily  attacked  by  alkalies. 

Chromium  sesquioxide — Green  oxide — Cr203— is  obtained,  amor- 
phous, by  calcining  a  mixture  of  potassium  dichromate  and  starch,  or 
crystallized  by  heating  neutral  potassium  chromate  to  redness  in  chlorine. 

It  is  green;  insoluble  in  water,  acids,  and  alkalies;  fusible  with  diffi- 
culty, and  not  decomposed  by  heat;  not  reduced  by  hydrogen.  At  a 
red  heat  in  air,  it  combines  with  alkaline  hydrates  and  nitrates  to  form 
chromates.  It  forms  two  series  of  salts,  the  terms  of  one  of  which  are 
green,  those  of  the  other,  violet.  The  alkaline  hydrates  separate  a  blu- 
ish green  hydrate  from  solutions  of  the  green  salts,  and  a  bluish  violet 
hydrate  from  those  of  the  violet  salts. 

Chromium  green,  or  emerald  green,  is  a  brilliant  green  hydrate,  formed 
by  decomposing  a  double  borate  of  chromium  and  potassium  by  water. 
It  is  used  in  the  arts  as  a  substitute  for  the  arsenical  greens,  and  is  non- 
poisonous. 

Chromic  anhydride,  CrO3 — improperly  called  chromic  acid,  is  pre- 
pared by  slowly  adding  one  and  one-half  parts  of  strong  sulphuric  acid  to 
one  part  of  a  concentrated  solution  of  potassium  dichromate,  draining  the 
crystals  on  a  porous  tile,  and  purifying  by  solution  in  water,  exact  pre- 
cipitation by  barium  chromate,  and  crystallization  over  sulphuric  acid. 

It  forms  deliquescent,  crimson  prisms,  very  soluble  in  water,  soluble 
in  alcohol.  It  is  a  powerful  oxidant,  capable  of  igniting  strong  alcohol. 

The  true  chromic  acid  has  not  been  isolated,  but  salts  corresponding  to 
three  acid  hydrates  are  known:  GrO  £1^= chromic  acid;  Cr207Ha^ di- 
chromic acid  •  Cr8O10H9=£rMJ/ir0raee  acid. 

Chlorides. — Two  chlorides  and  one  oxychloride  of  chromium  are 
known.  Chromous  chloride,  CrCl2,  is  a  white  solid,  soluble  with  a  blue 
color  in  water.  Chromic  chloride,  (Cr2)Cl6,  forms  large,  red  crystals,  in- 
soluble in  water  when  pure. 

Sulphates. —  A  violet  sulphate  crystallizes  in  octahedra,  (SO4)3(Cr)2 
+  15  Aq.,  and  is  very  soluble  in  water;  at  100°  it  is  converted  into  a 
green  salt,  (SO4)3(Cr)2  +  5  Aq.,  soluble  in  alcohol,  which  at  higher  temper- 
atures is  converted  into  the  red,  insoluble,  anhydrous  salt.  Chromic  sul- 
phate forms  double  sulphates,  containing  24  Aq.,  with  the  alkaline  sul- 
phates (see  Alums). 

Analytical  Characters. — CHROMOUS  SALTS:  Potash,  brown  pre- 
cipitate; Ammonium  hydrate,  greenish  white  precipitate;  Alkaline  sul- 
phides, black  precipitate;  Sodium  phosphate,  blue  precipitate. 

CHROMIC  SALTS. — Potash,  green  precipitate;  excess  of  precipitant 
forms  green  solution,  from  which  sesquioxide  separates  on  boiling;  Am- 
monium hydrate,  greenish  gray  precipitate;  Ammonium  sulphydrate, 
greenish  precipitate. 

CHROMATES. — Hydrogen  sulphide,  in  acid  solution,  brownish  color, 
changing  to  green;  Ammonium  sulphydrate,  greenish  precipitate;  J>a- 
rium  chloride,  yellowish  precipitate;  Silver  nitrate,  brownish  red  precipi- 


370  GENERAL    MEDICAL    CHEMISTRY. 

tate,  soluble  in  nitric  acid  and  in  ammonia;  Lead  acetate,  yellow  pre- 
cipitate, soluble  in  potash,  insoluble  in  acetic  acid. 

Action  on  the  economy. —  Chromic  anhydride  oxidizes  organic 
substances,  and  is  used  as  a  caustic. 

The  chromates,  especially  potassium  dichromate  (q.  v.),  are  irritants, 
and  have  a  distinctly  poisonous  action  as  well.  Workmen  handling  the 
dichromate  are  liable  to  a  form  of  chronic  poisoning. 

In  acute  chromium-poisoning,  emetiqs,  and  subsequently  magnesium 
carbonate  in  milk,  are  to  be  given. 


MANGANESE. 
Mn 55.2 

A  grayish,  brittle  metal,  hard,  fusible  with  difficulty;  sp.  gr.  7.138  — 
7.206;  obtained  by  reduction  of  its  oxides.  When  pure,  it  is  not  altered 
by  dry  air  in  the  cold,  but  is  superficially  oxidized  when  heated.  It  de- 
composes water,  especially  when  heated,  and  dissolves  in  dilute  acids. 

Oxides. — Manganese  forms  six  oxides,  or  compounds  representing 
them:  Manganous  oxide,  MnO;  Manganoso -manganic  oxide,  Mn3G4; 
Manganic  oxide,  Mn2O3;  Permanganic  oxide,  MnO2;  Manganic  anhy- 
dride, MnO3;  Permanganic  anhydride,  Mn2O7. 

PERMANGANIC  OXPDE. — Manganese  dioxide,  Black  oxide  of  manga- 
nese,  Mn02,  exists  in  nature  as  pyrolusite,  the  principal  ore  of  manganese, 
in  steel-gray  or  brownish,  imperfectly, crystalline  masses. 

At  a  red  heat  it  loses  12  per  cent,  of  oxygen,  and  .is  converted  into 
Mn304,  which,  at  a  white  heat,  yields  a  further  quantity  of  oxygen,  leav- 
ing MnO.  Heated  with  sulphuric  acid,  it  gives  off  oxygen  and  forms 
manganous  sulphate.  With  hydrochloric  acid,  it  yields  manganous 
chloride,  water,  and  chlorine.  With  sulphuric  and  oxalic  acids,  it  forms 
manganous  sulphate,  water,  and  carbon  dioxide.  It  forms  three  hy- 
drates, one  of  which  corresponds  to  a  series  of  salts,  called  manganites, 
MnAjM,. 

Neither  manganic  anhydride,  nor  manganic  acid,  Mn04H2,  have 
been  separated;  they  are,  however,  represented  by  well-defined  salts,  the 
manganates,  MnO4M2. 

Permanganic  anhydride  is  an  unstable,  green  liquid,  and  an  active 
oxidant.  Permanganic  acid,  MnO4H,  is  obtained  in  solution  by  decom- 
position of  its  barium  salt,  by  sulphuric  acid  (see  Potassium  permanga- 
nate). 

Salts. — Like  iron,  manganese  forms  two  series  of  salts:  Manganous 
salts,  containing  Mn";  and  manganic  salts,  containing  (Mn2)vi;  the  former 
are  colorless  or  pink,  and  soluble  in  water;  the  latter  are  quite  unstable. 

MANGANOUS  SULPHATE,  So4Mn. — is  formed  by  the  action  of  sulphuric 
acids  upon  the  oxides  of  manganese.  Below  6°  it  crystallizes  with  7  Aq., 
and  is  isomorphous  with  ferrous  sulphate;  between  7°  and  20°  it  forms 
crystals  with  5  Aq.,  and  is  isomorphous  with  cupric  sulphate;  between 
20°  and  30°  it  crystallizes  with  4  Aq.  It  is  rose-colored,  darker  as  the 
proportion  of  Aq.  increases,  soluble  in  water,  insoluble  in  alcohol.  With 
the  alkaline  sulphates  it  forms  double  salts  with  6  Aq. 

Analytical  Characters. — MANGANOUS. — Potash. — White  precipi- 
tate, turning  brown.  Alkaline  carbonates,  white  precipitate.  Ammo- 
nium sulphydrate,  flesh-colored  precipitate,  soluble  in  acids,  sparingly 


IKON.  377 

soluble  in  excess  of  precipitant.  Potassium  ferrocyanide,  reddish  white 
precipitate,  soluble  in  hydrochloric  acid.  Potassium  ferricyanide,  brown 
precipitate.  Potassium  cyanide,  rose-colored  precipitate,  forming  brown 
solution  in  excess. 

MANGANIC.  —  Hydrogen  sulphide,  precipitate  of  sulphur.  Ammo- 
nium sulphydrate,  flesh- colored  precipitate.  Potassium  ferrocyanide, 
greenish  precipitate.  Potassium ferricyanide^  brown  precipitate.  Potas- 
sium cyanide,  light  brown  precipitate. 

The  MANGANATES  are  green  salts,  whose  solutions  are  only  stable  in 
presence  of  excess  of  alkali,  and  turn  brown  when  diluted  and  acidulated. 
The  PERMANGANATES  form  red  solutions,  which  are  decolorized  by  redu- 
cing agentsfand  by  many  organic  substances;  sulphurous  acid  turns  them 
green. 


IRON. 
Fe 56 

The  principal  ores  of  iron  are:  red  haematite,  sesquioxide;  spathic  ore, 
ferrous  carbonate;  £0/7  ore,  ferrous  carbonate,  mixed  with  clay;  oolitic 
iron  and  brown  haematite,  hydrates  of  the  sesquioxide;  magnetic  or  black 
ore,  pyrites,  and  meteoric  iron. 

In  working  the  ores,  reduction  is  first  effected  in  a  blast-furnace,  into 
which  alternate  layers  of  ore,  coal,  and  limestone  are  fed  from  the  top, 
while  air  is  forced  in  from  below.  In  the  lower  part  of  the  furnace  car- 
bon dioxide  is  produced  at  the  expense  of  the  coal;  higher  up  it  is  re- 
duced by  the  incandescent  fuel  to  carbon  monoxide,  which  at  a  still 
higher  point  reduces  the  ore;  the  fused  metal  so  liberated  collects  at  the 
lowest  point  under  a  layer  of  slag,  and  is  drawn  off  to  be  cast  as  pig  iron. 
This  product  is  then  purified  by  burning  out  impurities  in  the  process 
known  as  puddling. 

Iron  is  used  in  the  arts  in  three  forms:  Cast  iron,  a  brittle,  crystalline 
material,  containing  carbon,  silicon,  phosphorus,  and  sulphur.  Wrought 
iron,  a  fibrous,  tough  variety,  freed  to  a  great  extent  from  the  impuri- 
ties of  cast  iron,  although  not  chemically  pure.  Steel  is  iron  combined 
with  a  small  quantity  of  carbon.  It  is  prepared  either  by  cementation, 
which  consists  of  causing  a  pure  iron  to  combine  with  carbon;  or  by  the 
JBessemer  method,  which  consists  in  burning  the  proper  quantity  of  car- 
bon out  of  cast  iron.  Pure  iron  is  obtained  by  heating  ferric  oxide  nearly 
to  redness  in  a  current  of  hydrogen;  this  is  the  ferrum  redactum  (U.  S., 
Br.).  The  purest  forms  of  commercial  iron  are  those  used  in  piano-strings, 
electro- magnets,  and  the  teeth  of  carding-machines.  The  finely  divided 
iron  by  alcohol  is  produced  by  mechanical  division  and  levigation  in 
alcohol. 

Pure  iron  is  quite  soft;  fuses  at  about  1600°;  crystallizes  in  cubes  or 
octahedra;  is  very  tenacious;  sp.  gr.  7.25 — 7.9. 

Iron  is  not  altered  by  dry  air  at  ordinary  temperatures;  at  a  red  heat 
it  is  oxidized;  in  damp  air  it  is  converted  into  a  hydrate,  known  as  rust. 
Tin  plate  is  sheet  iron  coated  with  tin ;  galvanized  iron  is  protected  by  a 
coating  of  zinc.  Iron  unites  directly  with  chlorine,  bromine,  iodine,  sul- 
phur, and  the  elements  of  the  phosphorus  group.  Hydrochloric  acid 
dissolves  it  as  ferrous  chloride,  while  hydrogen  is  liberated.  Heated 
with  strong  sulphuric  acid,  it  gives  off  sulphur  dioxide;  with  the  dilute 


378  GENERAL   MEDICAL    CHEMISTRY. 

acid,  hydrogen  is  given  off  and  ferrous  sulphate  formed.     Dilute  nitric 
acid  dissolves  iron,  but  the  concentrated  acid  renders  it  passive,  when  it 
1  is  no  longer  attacked  by  a  dilute  acid  until  the  passive  condition  is  de- 
stroyed by  contact  with  platinum,  silver,  or  copper,  or  by  heating  to  40°. 

Oxides. — Five  oxides  of  iron  are  known,  three  of  which  are  of  interest. 

FERROUS  OXIDE,  FeO — is  formed  by  heating  ferric  oxide  in  carbon 
mon-  or  dioxide.  Its  hydrate,  FeH2O2,  is  a  greenish  white  substance, 
formed  when  a  ferrous  salt  is  decomposed  by  an  alkaline  hydrate. 

FERRIC  OXIDE — Sesquioxide  or  Peroxide  of  iron — Fe2O3. — When  fer- 
rous sulphate  is  heated,  it  turns  white  by  loss  of  Aq. ;  then  yellow,  owing 
to  formation  of  an  oxy  hydrate;  then  brick -red,  when  it  has  beyi  converted 
into  ferric  oxide;  another  product  being  Nordhausen  sulphuric  acid. 

Under  the  names  colcothar,  red  crocus,  jeweller's  rouge,  and  Venetian 
red,  it  is  used  as  a  polishing  material  and  as  a  pigment. 

The  normal  hydrate — Ferri  peroxidum  humidum  (U.  S.,  Br.) — (Fea) 
H606 — is  a  brown,  gelatinous  precipitate,  formed  when  an  alkali  is  added 
to  a  ferric  salt.  When  dried  at  100°  it  loses  2H2O,  and  is  converted  into 
Ferri  peroxidum,  hydratum  (U.  S.,  Br.),  (Fe2)02,H2O2.  Ferric  hydrate  is 
not  precipitated  in  presence  of  fixed  organic  acids,  or  of  sugar  in  sufficient 
quantity.  Under  water  it  is  converted  into  an  oxyhydrate,  which  is  in- 
capable of  forming  ferrous  arsenate  with  arsenic  trioxide. 

A  peculiar  modified  ferric  hydrate,  (Fe2)O2H2O2,  is  formed  by  drying 
the  ordinary  hydrate  in  vacuo  and  boiling  it  seven  or  eight  hours  in 
water;  after  washing,  it  is  almost  insoluble  in  nitric  and  hydrochloric  acids, 
and  gives  no  Prussian  blue  reaction;  it  dissolves  in  dilute  acetic  acid, 
the  solution  being  reddish  and  appearing  turbid  by  reflected  light. 

Recently  precipitated  ferric  hydrate  dissolves  in  solutions  of  ferric 
chloride  or  acetate,  and  the  solutions,  by  dialysis,  lose  their  acid,  leaving 
in  the  dialyser  a  dark  red  solution  of  ferric  hydrate.  The  dialysed  iron 
so  obtained  is  coagulated  by  heat,  by  sulphuric  acid,  alkalies,  and  many 
salts. 

FERRIC  ANHYDRIDE — Fe203,  and  FERRIC  ACID — Fe2O4H2,  are  un- 
known, but  are  represented  by  potassium  ferrate,  Fe2O4K2. 

Sulphides. — Eight  sulphides  of  iron  are  known,  of  which  three  are 
of  interest. 

FERROUS  SULPHIDE — Protosulphide — FeS — is  formed:  1st,  by  bring- 
ing a  mixture  of  sulphur  and  iron  filings  into  a  red-hot  crucible;  2d,  by 
pressing  roll-sulphur  upon  white-hot  iron;  3d,  by  precipitating  a  ferrous 
salt  with  an  alkaline  sulphydrate.  The  dry  methods  form  brownish, 
brittle,  fusible,  magnetic  masses;  the  wet  method  yields  a  black  powder. 

It  is  not  decomposed  by  heat;  is  oxidized  by  damp  air;  is  decomposed 
by  dilute  sulphuric  acid,  with  formation  of  ferrous  sulphate  and  hydrogen 
sulphide.  It  occurs  in  the  fseces  of  persons  taking  chalybeate  waters  and 
preparations  of  iron. 

FERRIC  SULPHIDE — Sesquisulphide — Fe2S3 — occurs  in  nature  in  copper 
pyrites,  and  is  formed  when  the  disulphide  is  heated  to  redness. 

IRON  DISULPHIDE — Martial  pyrites — FeS2 — occurs  in  yellow  and  white 
pyrites,  which  are  extensively  used  in  the  manufacture  of  sulphuric  acid. 

Chlorides. — Two  chlorides  of  iron  are  known:  FeCl,  and  (Fe2)Cl0. 

FERROUS  CHLORIDE,  FeCl, — is  formed  when  iron  is  heated  to  redness 
in  dry  hydrochloric  acid,  or  with  sal-ammoniac,  as  an  anhydrous,  yellow- 
ish, crystalline,  volatile,  and  very  soluble  substance.  A  hydrated  com- 
pound, FeCl2  +  4Aq.,  is  formed  by  solution  of  the  anhydrous  chloride,  or 
by  solution  of  iron  in  hydrochloric  acid.  It  crystallizes  in  greenish,  ob- 


IRON.  379 

lique  rhombic  prisms;  loses  its  water  when  heated  without  contact  of 
air;  heated  in  air  it  is  converted  into  ferric  chloride  and  an  oxychloride. 

FERRIC  CHLORIDE  —  Sesquichloride  —  Perchloride  — Ferri  chloridum 
(U.  S.) — Fe2Cl6 — is  obtained  anhydrous  by  heating  iron  in  chlorine;  in 
violet,  volatile,  deliquescent  plates.  The  hydrated  compound,  Fe2Cl6-h 
4Aq.,  is  formed:  1st,  by  solution  of  the  anhydrous;  2d,  by  dissolving 
iron  in  aqua  regia;  3d,  by  dissolving  hydrated  ferric  oxide  in  hydro- 
chloric acid;  4th,  by  the  action  of  chlorine  or  of  nitric  acid  on  solution 
of  ferrous  chloride;  it  is  prepared  pharmaceutically  by  the  last  method. 

It  forms  yellow,  nodular  masses,  or  rhombic  plates,  very  soluble  in 
water,  soluble  in  alcohol  and  ether.  The  Liq.  ferri  chloridi  (U.  S.),  or 
Liq.  ferri  perchloridi  (Br.),  is  an  aqueous  solution  containing  excess  of 
acid.  The  Tinct.  ferri  chloridi  (U.  S.)  is  the  liquor  diluted  with  alcohol, 
and  contains  ethyl  chloride  and  ferrous  chloride. 

Bromides. — These  are  similar  in  composition  to  the  chlorides.  Fer- 
rous bromide,  FeBr2,  is  formed  by  the  action  of  bromine  on  excess  of 
iron  in  presence  of  water.  Ferric  bromide,  FeaBr6,  is  obtained  by  the 
action  of  excess  of  bromine  on  iron. 

Iodides. — Ferrous  iodide — Ferri  iodidum  (Br.) — FeI2 — is  obtained 
with  4Aq.,  by  adding  iodine  to  excess  of  iron  under  warm  water  until 
the  solution  is  pale  green.  Ferric  iodide,  Fe2I6,  is  formed  by  the  action 
of  excess  of  iodine  on  iron. 

Salts.  —  FERROUS  SULPHATE  —  Protosidphate —  Green  vitriol —  Cop- 
peras— Ferri  sidphas  (U.  S.,  Br.) — S04Fe — is  obtained  by  oxidation  of 
the  sulphide  remaining  in  the  manufacture  of  sulphuric  acid,  and  as  a 
by-product  in  other  processes.  When  required  pure,  it  is  prepared  by 
dissolving  iron  in  dilute  sulphuric  acid,  and  purifying  by  crystallization. 

It  crystallizes  in  oblique,  rhombic  prisms  with  7  Aq. ;  it  loses  6  Aq.  at 
100°,  and  the  last  Aq.  at  300°;  at  a  red  heat  it  is  decomposed  into  ferric 
oxide,  and  sulphur  di-  and  trioxides.  It  is  soluble  in  water,  insoluble  in 
alcohol.  By  exposure  to  air  it  is  gradually  converted  into  a  basic  ferric 
sulphate,  (SO4)8(Fea),5FeaOa. 

FERRIC  SULPHATES  are  quite  numerous,  and  are  formed  by  oxidation 
of  ferrous  sulphate  under  different  conditions.  The  normal  sulphate, 
(S04)3(Fe2),  is  formed  by  treating  ferrous  sulphate  solution  with  nitric 
acid,  and  evaporating  after  addition  of  one  molecule  of  sulphuric  acid  for 
each  two  molecules  of  ferrous  sulphate;  its  solution  is  the  Liq.  ferri 
tersulphatis  (U.  S.).  Among  the  basic  sulphates  is  one  prepared  by  a 
process  similar  to  the  above,  using  half  the  quantity  of  sulphuric  acid, 
which  exists  in  Liq.  ferri  subsulphatis  (U.  S.),  or  MonseVs  solution. 

Ferric  sulphate  forms  alums  with  the  alkaline  sulphates. 

FERROUS  NITRATE,  (N03)2Fe — a  greenish,  unstable  salt,  formed  by 
double  decomposition  between  barium  nitrate  and  ferrous  sulphate;  or 
by  the  action  of  nitric  acid  on  ferrous  sulphide. 

FERRIC  NITRATES. — The  normal  nitrate,  (NO3)6(Fe2),  is  formed  along 
with  ferrous  nitrate  by  solution  of  iron  in  nitric  acid.  The  Liq.  ferri 
nitratis  (U.  S.),  or  Liq.  ferri pernitratis  (Br.),  contains  ferric  nitrate,  and 
is  made  with  an  acid  of  sp.  gr.  1.115.  It  crystallizes  in  rhombic  prisms 
with  18  Aq.  or  in  cubes  with  12  Aq.  When  iron  is  dissolved  in  nitric 
acid  to  saturation,  basic  nitrates  are  formed,  which  prevent  crystallization 
of  the  normal  salt. 

TRIFERROUS  PHOSPHATE,  (PO4)?Fe3 — a  white  precipitate  formed  by 
adding  disodic  phosphate  to  a  solution  of  a  ferrous  salt.  By  exposure  to 
air  it  turns  blue,  a  part  being  converted  into  ferric  phosphate;  the  ferri 


380  GENERAL    MEDICAL    CHEMISTRY. 

phosphas  (U.  S.,  Br.)  is  such  a  mixture  of  the  two  salts.  It  is  insoluble 
in  water,  sparingly  soluble  in  water  containing-  carbonic  and  acetic  acids. 

A  phosphate  of  iron,  capable  of  turning  blue,  occurs  in  the  lungs  in 
phthisis,  in  blue  pus,  and  in  long-buried  bones. 

FERRIC  PHOSPHATE,  (PO4),(F«f) — is  formed  by  the  action  of  an  alka- 
line phosphate  on  ferric  chloride.  It  is  soluble  in  hydrochloric,  nitric, 
citric,  and  tartaric  acids;  insoluble  in  phosphoric  acid. 

FERRIC  PYROPHOSPHATE,  lfPjO<),(F^1 — is  formed  by  decomposition 
of  a  ferric  salt  by  sodium  pyrophosphate;  an  excess  of  the  sodium  salt 
dissolves  the  precipitate  when  warmed,  and  on  evaporation  leaves  scales  of 
a  double  salt,  (PaO7)s(Fe,)a,  (P2O7)2Na?  +  20Aq.  A  similar  ammonium  salt, 
accompanied  by  ferric  citrate,  exists  in  the  ferri pyrophosphas  (U.  S.). 

FERROUS  ACETATE,  (02H3O2)2Fe — is  formed  by  decomposition  of  fer- 
rous sulphate  by  calcium  acetate.  It  crystallizes  in  soluble,  silky  needles. 

FERRIC  ACETATES. — The  normal  salt,  (C2H3O2)e,(FeQ),  is  obtained  by 
adding  slight  excess  of  ferric  sulphate  to  lead  acetate,  and  decanting  after 
twenty-four  hours.  It  is  dark  red,  uncrystallizable,  very  soluble  in  alco- 
hol and  in  water.  If  its  solution  be  heated  it  darkens  suddenly,  gives  off 
acetic  acid,  and  contains  a  basic  acetate;  when  boiled  it  loses  all  its  acetic 
acid  and  deposits  ferric  hydrate;  when  heated  in  closed  vessels  to  100°, 
and  treated  with  a  trace  of  mineral  acid,  it  deposits  the  modified  ferric 
hydrate. 

FERROUS  CARBONATE,  C03Fe — is  obtained  in  the  hydrated  form  by 
adding  an  alkaline  carbonate  to  a  ferrous  salt  ;  on  exposure  to  air  it 
turns  red  from  formation  of  ferric  hydrate.  It  is  insoluble  in  pure  water, 
but  soluble  in  water  containing  carbonic  acid,  probably  as  a  bicarbonate, 
in  which  form  it  exists  in  mineral  waters.  The.  ferri  carbonas  saccharata 
(Br.)  is  this  salt,  to  which  sugar  is  added  to  delay  decomposition  ;  the 
ferri  subcarbonas  (U.  S.)  is  ferrous  hydrate. 

FERROUS  LACTATE  —  Ferri  lactas  (U.  S.)— (C3H5O3)2Fe  +  3Aq.— is 
formed  by  dissolving  iron  filings  in  lactic  acid.  It  crystallizes  in  light 
yellow  needles,  soluble  in  water,  insoluble  in  cold  alcohol  ;  permanent  in 
air  when  dry. 

FERROUS  OXALATE — Ferri  oxalas  (U.  S.) — C204Fe  +  2Aq. — is  formed 
by  dissolving  iron  in  solution  of  oxalic  acid.  It  is  a  bright  yellow,  crystal- 
line powder,  sparingly  soluble  in  hot  water. 

FERROUS  TARTRATE,  C4H4O6Fe  +  2Aq. — a  white,  crystalline  powder, 
formed  by  dissolving  iron  in  hot,  strong  solution  of  tartaric  acid. 

FERRIC  TARTRATE,  (04H4O6)3  (Fe2)  -f  3Aq. — a  dirty  yellow,  amorphous 
mass,  obtained  by  dissolving  recently  precipitated  ferric  hydrate  in  tar- 
taric acid,  and  evaporating  below  50°.  Its  solution  is  not  precipitated  by 
alkalies  or  alkaline  carbonates. 

A  number  of  double  tartrates,  containing  the  group  (Fe202)"  are  also 
known.  Such  are  :  Ferrico-ammonic  tartrate;  ferri  et  ammonii  tartras 
(U.S.),  (C4H406)2(Fe20,),(NH4)2  +  4Aq.,  and  Ferrico-potassic  tartrate; 
ferri  et  potassii  tartras  (U.  S.),  (C4H40?)2  (Fe2O2)K2  ;  they  are  prepared 
by  dissolving  recently  precipitated  ferric  hydrate  in  hot  solutions  of  the 
hydro-alkaline  tartrate.  They  only  react  with  ferro-  and  sulphocyanides 
after  addition  of  a  mineral  acid. 

FERRIC  FERROCYANIDE — Ferri  f  err  ocyanidum  (U.  S.) — Prussian  blue 
— (FeC6N6)3  (Fe2)2  +  18Aq. — a  dark  blue  precipitate  formed  when  potas- 
sium ferrocyanide  is  added  to  a  ferric  salt.  It  is  insoluble  in  water,  alco- 
hol, ether,  and  dilute  acids;  soluble  in  oxalic  acid  (blue  ink);  alkalies 
turn  it  brown. 


ALUMINIUM.  381 

FERROUS  FERRICYANIDE — TurnbuWs  blue — (Fe2C12N1?)  Fe3-hnAq. — a 
dark  blue  precipitate,  produced  by  potassium  ferricyanide  with  ferrous 
salts. 

ANALYTICAL  CHARACTERS. — FERROUS  SALTS  are  acid,  colorless  when 
anhydrous,  pale  green  when  hydrated  ;  oxidized  by  air  to  basic  ferric 
compounds.  Potash,  greenish  white  precipitate,  insoluble  in  excess, 
changing  to  brown  in  air.  Ammonium  hydrate,  greenish  precipitate, 
soluble  in  excess,  not  formed  in  presence  of  ammoniacal  salts.  Ammo- 
nium sulphydrate,  black  precipitate,  soluble  in  acids.  Potassium  fer- 
rocyanide,  white  precipitate,  turning  blue  in  air.  Potassium  ferricy- 
anide, blue  precipitate,  soluble  in  potash,  insoluble  in  hydrochloric  acid. 

FERRIC  SALTS  are  acid,  and  yellow  or  brown.  Potash  or  ammonium 
hydrate,  voluminous,  red-brown  precipitate.  Hydrogen  sulphide  in  acid 
solution,  milky  deposit  of  sulphur,  ferric  reduced  to  ferrous  compound. 
Ammonium  sulphydrate,  black  precipitate.  Potassium  ferrocyanide, 
dark  blue  precipitate,  insoluble  in  hydrochloric  acid,  soluble  in  potash. 
Potassium  sulphocyanate,  dark  red  color  ;  prevented  by  tartaric  and 
citric  acids.  Tannin,  blue-black  color. 


III.  ALUMINIUM  GROUP. 


GLUCINIUM Gl 13.8 

ALUMINIUM.          ,.A1..         ..27.5 


GALLIUM Ga 69.9 

INDIUM.  ..In..          ..113.4 


This  group  is  placed  in  the  third  class  by  virtue  of  the  existence  of 
the  aluminates,  and  of  the  relations  between  the  compounds  of  these  ele- 
ments and  some  of  those  of  the  previous  groups.  They  form,  however, 
but  one  series  of  compounds,  corresponding  to  the  ferric,  containing  the 
group  (M2)vi.  No  acids  or  salts  of  the  members  of  the  group,  other  than 
aluminium,  are  known;  yet  their  resemblances  in  other  points  are  such  as 
to  forbid  their  separation. 


ALUMINIUM. 
Al 27.5 

This,  the  only  element  of  the  group  of  practical  importance,  although 
very  abundant  in  combination,  was  only  isolated  in  1817  by  Woehler,  by 
a  method  which  has  since  become  general  for  the  separation  of  metals 
whose  compounds  are  difficultly  reducible,  which  consists  in  passing  the 
vapor  of  the  chloride  over  sodium  heated  to  redness. 

Aluminium  is  a  bluish  white  metal  ;  hard,  very  malleable  and  ductile 
when  annealed  from  time  to  time  ;  slightly  magnetic  ;  a  good  conductor 
of  electricity  ;  fuses  at  about  700°;  non-volatile  ;  sp.  gr.  2.56  when  cast, 
2.67  when  rolled.  It  is  not  affected  by  air  or  oxygen,  except  at  very 
high  temperatures,  and  even  then  very  superficially.  If,  however,  it 
contain  silicon,  it  burns  readily,  forming  aluminium  silicate.  Boron, 
silicon,  and  the  elements  of  the  chlorine  group  combine  with  it  directly. 
It  does  not  decompose  water  at  a  red  heat.  Hydrochloric  acid,  gaseous 
or  in  solution,  attacks  it,  hydrogen  is  given  off,  and  aluminium  chloride 
formed.  It  dissolves  readily  in  alkaline  solutions  with  liberation  of  hy- 
drogen and  formation  of  aluminates.  It  unites  with  copper  to  form  a 


382  GENERAL   MEDICAL    CHEMISTRY. 

golden  yellow  alloy,  known  as  aluminium  bronze.  The  great  toughness 
and  lightness  of  aluminium  and  of  its  alloys  render  it  valuable  for  the 
manufacture  of  metallic  objects  where  lightness  is  desirable. 

Aluminium  oxide — Alumina — A12O3 — exists  in  nature,  nearly  pure, 
in  corundum,  emery,  ruby,  sapphire,  and  topaz.  It  is  obtained  artificially 
by  calcining  the  hydrate,  and  is  also  formed  when  ammonia  alum  (q.  v.)  is 
calcined  at  a  red  heat.  It  is  a  light,  white,  odorless,  tasteless  powder,  fuses 
with  difficulty,  and,  on  cooling,1  forms  crystals  which  are  hard  enough  to 
scratch  glass.  Unless  it  have  bsen  heated  beyond  dull  redness,  it  combines 
with  water,  the  union  being  attended  with  liberation  of  heat.  It  is  at- 
tacked with  great  difficulty  by  acids,  its  best  solvent  being  sulphuric 
acid  diluted  with  its  weight  of  water.  It  also  dissolves  with  difficulty  in 
alkaline  solutions,  but  combines  with  fused  potash  and  soda  to  form  alumi- 
nates.  It  is  not  reduced  by  charcoal. 

Aluminium  hydrate,  A12H606 — is  formed  when  a  solution  of  an 
aluminium  salt  is  precipitated  by  ammonium  hydrate  or  carbonate.  It 
forms  a  gelatinous  precipitate  which,  when  washed  and  dried,  leaves  an 
amorphous,  translucid  mass.  When  it  is  formed  in  the  presence  of  color- 
ing matters,  these  are  mechanically  carried  down  with  it,  and  the  dried 
deposits  are  used  as  pigments,  known  as  lacs  •  it  is  insoluble  in  water 
when  freshly  precipitated;  soluble  in  acids  and  solutions  of  the  fixed 
alkalies.  With  the  acids  it  forms  salts  of  aluminium;  and  with  the 
alkalies,  aluminates  of  the  alkaline  element.  When  heated  to  near  red- 
ness it  is  decomposed  into  aluminium  oxide  and  water.  A  soluble  variety 
of  alu*mina  has  been  obtained  by  dialysing  a  solution  of  alumina  in  alu- 
minium chloride  solution,  or  by  heating  for  240  hours  a  dilute  solution  of 
aluminium  acetate. 

Aluminates  are  for  the  most  part  crystalline,  soluble  compounds, 
obtained  by  the  action  of  metallic  oxides  or  hydrates  upon  alumina.  Potas- 
sium aluminate,  Al204K2  +  3Aq. — is  formed  by  dissolving  recently  pre- 
cipitated aluminium  hydrate  in  potash  solution.  It  forms  white  crystals; 
very  soluble  in  water,  insoluble  in  alcohol;  caustic  and  alkaline.  By  a 
large  quantity  of  water  it  is  decomposed  into  aluminium  hydrate  and  a 
more  alkaline  salt,  A1409K6.  Sodium  aluminate. — The  aluminate  Ala 
04Na2  is  not  known.  That  having  the  composition  Al4O9Na6is  prepared 
industrially,  for  use  in  dyeing,  by  heating  to  redness  a  mixture  of  one 
part  of  sodium  carbonate  and  two  parts  of  a  native,  ferruginous  alumin- 
ium hydrate  (beauxite).  It  is  insoluble  in  water,  and  is  decomposed  by 
carbonic  acid  with  precipitation  of  aluminium  hydrate. 

Aluminium  chloride,  A12C16 — is  prepared  industrially  as  a  step  in 
the  manufacture  of  aluminium.  It  crystallizes  in  colorless,  hexagonal 
prisms;  fusible;  volatile;  deliquescent;  very  soluble  in  water  and  in 
alcohol.  From  a  hot,  concentrated  solution  it  separates  in  prisms  con- 
taining 12  Aq.  It  absorbs  hydrogen  sulphide,  hydrogen  phosphide,  and 
ammonia,  with  which  it  forms  compounds. 

An  impure  solution  of  aluminium  chloride  is  used  as  a  disinfectant 
under  the  name  chloralum. 

Salts. — ALUMINIUM  SULPHATES,  (SO4)3Al2-f-18Aq. — is  prepared  arti- 
ficially on  a  large  scale  from  kaolin.  It  is  also  formed  (Aluminii  sulphas, 
U.  S.)  by  dissolving  aluminium  hydrate  in  moderately  diluted  sulphuric 
acid. 

It  crystallizes  with  difficulty  in  thin,  flexible  plates;  soluble  in  water, 
very  sparingly  soluble  in  alcohol.  When  heated,  it  fuses  in  its  water  of 
crystallization,  which  it  gradually  loses  up  to  200°,  when  a  white,  amor- 


ALUMINIUM.  383 

phous  powder  of  the  anhydrous  salt,   (S04)3A12,  remains;  this  at  a  red 
heat  is  decomposed,  leaving  a  residue  of  pure  alumina. 

Alums  are  double  sulphates  of  the  alkaline  metals,  and  the  higher 
sulphates  of  the  elements  of  this  and  the  preceding  group.  When  crys- 
tallized, they  contain  24  Aq.,  and  have  the  general  formula:  (S04)3(M2)V1, 
S04R'2  +  24Aq.,  in  which  (M2)  may  be  (Fe2),  (Mn2),  (O2),  (A12),  or  (Ga2); 
and  R2  may  be  K2,  Na2,  Rb2,  Cs2,  T12,  or  (NH4)2.  They  are  isomorphous. 

The  substance  formerly  known  as  alum  is  the  double  sulphate  of  alu- 
minium and  potassium,  (SO4)3  A12,  SO4K2-f-24Aq.  It  is  manufactured 
from  aluminous  schists,  from  clays  free  from  iron,  and  from  aluminite,  a 
native  subsulphate  of  aluminium  arid  potassium.  That  from  the  last- 
named  source  crystallizes  in  cubes,  and  is  known  as  cubic  or  Roman  alum. 
It  is  formed  when  concentrated  solutions  of  sulphates  of  aluminium  and 
of  potassium  are  mixed  in  suitable  proportions. 

It  crystallizes  in  large,  transparent,  regular  octahedra;  has  a  sweet- 
ish, astringent  taste;  100  parts  of  water  at  10°  dissolve  9.52  parts  of 
alum;  and  at  100°,  357.48  parts.  When  heated  to  about  92°,  it  fuses  in 
its  water  of  crystallization,  and  gradually  loses  45.5  per  cent,  of  its 
weight  of  water  as  it  is  heated  to  a  temperature  near  redness.  The  pro- 
duct, which  is  readily  pulverizable,  and  slowly  but  completely  soluble  in 
20 — 30  times  its  weight  of  water,  is  known  as  burnt  alum,  and  is  the  an- 
hydrous double  sulphate.  At  a  bright  red  heat,  sulphur  dioxide  and 
oxygen  are  given  off,  and  alumina  and  potassium  sulphate  remain.  At  a 
higher  temperature,  potassium  aluminate  is  formed.  Its  solutions,  acid 
in  reaction,  deposit  aluminium  hydrate  when  neutralized  with  ammonium 
hydrate. 

Potash  alum  is  giving  place  in  the  arts  to  the  cheaper  aluminium  and 
ammonium  sulphate,  or  ammonia  alum,  (SO4)3A12,  SO4(NH4)2-f-24Aq., 
which  differs  from  potash  alum  in  being  more  soluble  between  20°  and 
30°,  and  less  soluble  in  colder  or  warmer  water,  and  in  the  manner  in 
which  it  is  affected  by  heat.  It  fuses  in  its  water  of  crystallization,  as 
does  potash  alum;  at  about  205°,  the  temperature  reached  in  making 
burnt  alum,  it  loses  its  ammonium  sulphate,  leaving  a  white,  hygroscopic 
substance,  very  slowly  and  incompletely  soluble  in  water;  when  more 
strongly  heated,  it  leaves  alumina. 

Alum  and  the  alkaline  bicarbonates  decompose  each  other  with  for- 
mation of  aluminium  hydrate,  an  alkaline  sulphate,  and  carbon  dioxide,  a 
reaction  utilized  in  alum  baking-powders  (q.  v.). 

Silicates  are  very  abundant  in  the  different  varieties  of  clay,  f eld- 
spar,  albite,  labradorite,  mica,  etc.  The  clays  are  hydrated  aluminium 
silicates,  more  or  less  contaminated  with  alkaline  and  earthy  salts  and 
iron,  to  which  last  certain  clays  owe  their  color.  The  purest  is  kaolin, 
or  porcelain  clay,  a  white  or  grayish  powder.  They  are  largely  used  in 
the  manufacture  of  the  different  varieties  of  bricks,  terra  cotta,  pottery, 
and  porcelain.  Porcelain  is  made  from  the  purer  clays,  mixed  with  sand 
and  feldspar;  the  former  to  prevent  shrinkage,  the  latter  to  bring  the 
mixture  into  partial  fusion,  and  to  render  the  product  translucent.  The 
fashioned  articles  are  subjected  to  a  first  baking;  the  porous,  baked  clay 
is  then  coated  with  a  glaze,  usually  composed  of  oxide  of  lead,  sand, 
and  salt.  During  a  second  baking,  the  glaze  fuses  and  coats  the  article 
with  a  hard,  impermeable  layer.  The  coarser  articles  of  pottery  are 
glazed  by  throwing  sodium  chloride  into  the  fire;  the  salt  is  volatilized, 
and,  on  contact  with  the  hot  aluminium  silicate,  deposits  a  coating  of  the 
fusible  sodium  silicate,  which  hardens  on  cooling. 


384  GENERAL    MEDICAL    CHEMISTRY. 

ALUMINIUM  ACETATE,  (C2H3O2)6(A12) — is  obtained  only  in  solution, 
by  decomposing  a  concentrated  solution  of  aluminium  sulphate  with  lead 
acetate,  or  by  dissolving  aluminium  hydrate  in  acetic  acid.  It  is  an  un- 
crystallizable  liquid,  having  a  styptic  taste,  which  is  decomposed  when 
heated  or  on  standing,  with  formation  of  basic  acetates.  Is  extensively 
used  in  dyeing. 

Analytical  Characters.— Potash  or  soda,  white  precipitate,  soluble 
in  excess;  Ammonium  hydrate,  white^precipitate,  almost  insoluble  in 
excess,  especially  in  the  presence  of  ammoniacal  salts;  Sodium  phosphate, 
white  precipitate,  readily  soluble  in  potash  and  soda,  but  not  in  ammo- 
nium hydrate  ;  readily  soluble  in  mineral  acids,  but  not  in  acetic  acid; 
Blowpipe;  on  charcoal  does  not  fuse,  and,  when  moistened  with  solution 
of  cobalt  nitrate,  turns  dark  sky-blue. 


V.     LEAD   GROUP. 
LEAD Pb 207 

This  element  is  usually  classed  with  cadmium,  bismuth,  or  copper 
and  mercury;  it  differs,  however,  from  bismuth  in  being  divalent  or 
quadrivalent,  but  not  trivalent,  and  in  forming  no  compounds  resembling 
those  of  bismuthyl  (BiO);  from  cadmium  in  the  nature  of  its  oxygen 
compounds;  and  from  mercury  and  copper  in  forming  no  compounds 
similar  to  the  mercurous  and  cuprous  salts.  Indeed,  the  nature  of  the 
lead  compounds  is  such  that  the  element  is  best  classed  in  a  group  by  it- 
self, which  finds  a  place  in  this  class  by  virtue  of  the  existence  of  potas- 
sium plumbate. 

The  most  abundant  ore  of  lead  is  a  sulphide  known  as  galena,  which 
is  worked  for  lead  and  silver.  The  ore  is  roasted;  the  mixture  of  oxide, 
sulphide  and  sulphate  so  formed  is  heated  in  a  reverberatory  furnace, 
to  yield  an  impure  metal,  called  work-lead*  If  the  ore  be  rich  in  silver, 
it  is  subjected  to  refining  by  crystallization  and  cupellation.  At  first, 
the  work-lead  is  fused  and  allowed  to  cool  slowly;  crystals  of  lead  sepa- 
rate and  are  removed,  while  the  silver  remains  in  the  more  fusible  alloy. 
After  several  crystallizations,  the  concentrated  alloy  is  fused  in  the  cu- 
pelling furnace  and  a  powerful  current  of  air  is  driven  over  the  surface  of 
the  molten  metal;  the  lead  is  thus  oxidized  and  is  driven  off  by  the  cur- 
rent of  air  through  a  notch,  whose  depth  is  increased  as  the  operation 
proceeds.  As  the  last  film  of  lead  oxide  is  carried  off,  the  clear  surface  of 
the  fused  silver  is  exposed  and  the  mass  brightens,  indicating  the  termina- 
tion of  the  operation. 

Lead  is  a  grayish  white  metal;  brilliant  upon  freshly  cut  surfaces, 
very  soft  and  pliable,  not  very  malleable  or  ductile,  fuses  at  334°,  and, 
on  cooling,  crystallizes  in  octahedra;  a  poor  conductor  of  electricity;  a 
better  conductor  of  heat.  When  expanded  by  heat,  it  does  not,  on  cool- 
ing, return  to  its  original  volume. 

Lead,  when  exposed  to  air,  is  oxidized;  it  is  not  acted  on  by  pure 
water,  deprived  of  air;  by  the  combined  action  of  air  and  water,  lead  is 
oxidized  to  the  hydrate,  PbII202,  which  dissolves  to  an  appreciable  ex- 
tent. The  solvent  action  of  water  upon  lead  is  increased,  owing  to  the 
formation  of  basic  salts,  by  the  presence  of  nitrogenized  organic  matters, 
nitrates,  and  nitrites;  on  the  other  hand,  carbonates,  sulphates,  and  car- 
bon dioxide,  by  their  tendency  to  form  insoluble  coatings,  diminish  the 


LEAD. 


385 


solubility  of  the  metal  in  water.  Nitric  acid  dissolves  lead  readily;  sul- 
phuric acid,  when  cold,  does  not  affect  it;  but  when  heated,  dissolves  it 
the  more  readily  the  more  concentrated  the  acid.  Hydrochloric  acid  of 
sp.  gr.  1.12  attacks  it,  especially  if  heated. 

Several  alloys  of  lead  are  used  in  the  arts:  Type-metal=lead  and  anti- 
mony; pewten^lead  and  tin;  plumber's  solder=lead  and  tin. 

Oxides.— Lead  forms  five  oxides:  Pb2O,  PbO,  Pb3O4,  Pb,O3,  and  PbO2. 

LEAD  MONOXIDE — Protoxide — Massicot — Litharge — Plumbi  oxidum 
(U.  S.,  Br.)P — bO  is  prepared  by  calcining  lead  or  its  carbonate  or  nitrate. 
If  the  product  have  been  fused,  it  is  litharge  ;  if  not,  massicot ;  the  two 
varieties  differing  in  color  and  in  texture,  but  not  in  composition.  Mas- 
sicot is  prepared  by  calcining  lead  and  removing  the  pellicle  as  soon  as  it 
is  formed;  litharge,  by  fusing  massicot,  and  allowing  it  to  cool.  When 
fused,  it  crystallizes  in  mica-like  plates;  from  its  solution  in  soda  or 
potash,  it  is  deposited  in  white,  rhombic  dodecahedra  or  in  rose-colored 
cubes.  It  fuses  at  a  heat  approaching  redness;  it  volatilizes  at  a  white 
heat;  sp.  gr.  9.277;  after  fusion,  9.5.  It  is  sparingly  soluble  in  water, 
the  solution  being  alkaline  in  reaction. 

When  heated  to  300°  in  contact  with  air,  it  is  oxidized  to  minium. 
When  fused  in  earthen  crucibles  it  forms  a  fusible  silicate,  and  thus  per- 
forates the  vessel.  It  is  readily  reduced  by  charcoal  or  hydrogen. 
Chlorine  converts  it  into  the  chloride  with  separation  of  oxygen.  It  is  a 
powerful  base;  it  decomposes  the  alkaline  salts  with  liberation  of  the 
alkali;  it  dissolves  readily  in  nitric  acid  and  in  hot  acetic  acid,  with  form- 
ation of  nitrate  or  acetate.  When  rubbed  up  with  oils  it  decomposes 
the  gly eerie  ethers,  and  combines  with  the  fatty  acids  to  form  lead-soaps; 
one  of  which,  the  oleate,  is  the  emplastrum  plumbi  (U.  S.,  Br.).  It  also 
combines  with  the  alkalies  and  earths  to  form  plumbites.  Calcium 
plumbite,  Pb2O3Ca,  is  a  crystalline  compound,  formed  by  heating  litharge 
with  milk  of  lime.  Its  solution  is  used  as  a  hair-dye. 

PLUMBOSO -PLUMBIC  OXIDE — Red  oxide  of  lead — Minium — Red  lead — 
Pb304  or  PbO2,  2PbO  or  PbO3Pb-j-PbO— is  prepared  for  use  as  a  pig- 
ment, and  in  the  manufacture  of  glass,  by  heating  litharge  to  300°  in 
contact  with  air.  It  ordinarily  has  the  composition  given  above,  and  has 
been  considered  as  composed  of  one  molecule  of  the  dioxide  combined 
with  two  of  the  monoxide;  or  as  the  lead  salt  of  plumbic  acid  combined 
with  a  molecule  of  the  monoxide.  An  orange-colored  variety  is  formed 
by  heating  lead  carbonate  to  300°. 

It  is  a  brilliant  red  powder,  sp.  gr.  8.62.  When  strongly  heated  it 
is  converted  into  litharge;  a  change  which  is  also  brought  about  by  redu- 
cing agents.  Nitric  acid  changes  its  color  to  brown,  dissolving  the  mon- 
oxide and  leaving  the  dioxide.  Hydrochloric  acid  decomposes  it  with 
formation  of  chlorine,  lead  chloride,  and  water. 

The  commercial  product  is  frequently  contaminated  with  oxide  of 
iron  and  brick-dust.  It  should  dissolve  in  dilute  nitric  acid  to  which  a 
fragment  of  sugar  has  been  added. 

LEAD  DIOXIDE — Peroxide  of  lead — Puce  oxide  of  lead — JSinoxide  of 
lead — Plumbic  anhydride — PbO2 — is  prepared  either  by  dissolving  the 
monoxide  out  of  minium  by  dilute  nitric  acid,  or  by  passing  a  current 
of  chlorine  through  water  holding  lead  carbonate  in  suspension. 

It  is  a  dark,  reddish  brown  powder,   sometimes  crystalline;  sp.   gr. 
8.903  to  9.190;  insoluble  in  water.     When  heated  it  loses  half  its  oxygen 
and  is  converted  into  the  monoxide.     It  is  a  valuable  oxidizing  agent. 
It  absorbs  sulphur  dioxide  to  form  lead  sulphate. 
25 


38 C  GENERAL    MEDICAL    CHEMISTRY. 

PLUMBIC  ACID,  Pb03H3 — is  formed  in  crystalline  plates,  at  the  positive 
pole,  when  alkaline  solutions  of  the  lead  salts  are  decomposed  by  a  weak 
current. 

The  alkalies  dissolve  lead  dioxide  to  form  well-defined  but  unstable 
salts,  called  plumbates.  Potassium  plumbate,  PbO3K2  +  3Aq.,  is  obtained 
in  cubic  crystals  when  lead  dioxide  is  gently  heated  in  a  silver  vessel  with 
concentrated  potash  solution.  It  is  decomposed  by  water. 

Lead  Sulphide,  PbS — exists  an  naturj3  in  cubic  crystals  as  the  chief 
ore  of  lead,  galena.  It  is  also  formed  by  direct  union  of  the  elements;  by 
heating  lead  monoxide  with  sulphur  or  vapor  of  carbon  disulphide;  or  by 
decomposing  a  solution  of  a  lead  salt  with  hydrogen  sulphide  or  an  alka- 
line sulphydrate. 

The  native  sulphide  is  bluish  gray  and  has  a  metallic  lustre;  sp.  gr. 
7.58;  that  obtained  by  precipitation  is  a  black  powder  of  sp.  gr.  6.924. 
It  fuses  at  a  red  heat  "and  is  partially  sublimed,  partially  converted  into 
a  subsulphate  with  loss  of  sulphur.  When  heated  in  air  it  is  converted 
into  sulphate  and  oxide,  and  sulphur  dioxide.  Heated  in  hydrogen  it  is 
reduced.  Hot  nitric  acid  oxidizes  it  to  the  sulphate;  hot  hydrochloric 
acid  converts  it  into  the  chloride;  boiling  sulphuric  acid  converts  it  into 
the  sulphate  and  disengages  sulphur  dioxide. 

Chlorides. — Two  compounds  of  chlorine  and  lead  are  known,  PbCl. 
and  PbCl4. 

LEAD  CHLORIDE,  PbCl2 — is  formed  by  the  action  of  chlorine  upon 
lead  at  a  red  heat  by  the  action  of  boiling  hydrochloric  acid  upon  the 
metal;  and  by  double  decomposition  between  a  soluble"  salt  of  lead  and  a 
chloride.  In  the  last  case,  if  the  solutions  be  cold  and  not  too  dilute,  the 
chloride  is  precipitated. 

It  crystallizes  in  plates  or  in  silky,  hexagonal  needles;  soluble  in  135 
parts  of  water  at  12.5°;  less  soluble  in  water  containing  hydrochloric  acid; 
more  soluble  in  concentrated  hydrochloric  acid  and  in  boiling  water. 

Lead  also  forms  several  oxychlorides;  that  having  the  composition 
PbCl2,7PbO  is  used  as  a  pigment,  and  is  known  as  Cassel,  Paris,  Verona, 
or  Turner's  yellow. 

Iodide — Plumbi  iodidum(U.  S.,  Br.) — PbI2 — is  deposited  as  a  bright 
yellow  powder  when  a  solution  of  potassium  iodide  is  added  to  a  solu- 
tion of  a  lead  salt.  It  is  .almost  insoluble  in  cold  water,  sparingly  soluble 
in  boiling  water.  When  fused  in  air  it  loses  iodine  and  is  converted 
into  an  oxysalt.  When  exposed  to  light  and  moisture  it  is  decomposed 
with  liberation  of  iodine.  It  dissolves  in  solutions  of  ammonium  chlo- 
ride, sodium  hyposulphite,  alkaline  iodides,  and  potassium  hydrate. 

Salts. — NITRATES. — Besides  a  neutral  salt,  lead  forms  basic  nitrates, 
some  of  which  seem  to  indicate  the  existence  of  nitrogen  acids  similar  to 
those  of  phosphorus. 

(NO4)2Pb3,  Lead  orthonitrate (PO4)2Pb3,  Lead  orthophosphate. 

N2O,Pb.2,  Lead  pyronitrate P2O7Pb2,  Lead  pyrophosphate. 

(NO8)2Pb,  Lead  metanitrate (PO3)2Pb,  Lead  metaphosphate. 

Neutral  lead  nitrate — PlumUnitras  (U.  S.,Br.) — (NO3)2Pb — is  formed 
by  solution  of  lead  or  its  oxides  in  excess  of  nitric  acid.  It  forms  anhyd- 
rous crystals,  soluble  in  1.98  parts  water  at  17.5°,  and  in  0.7  parts  at  100°. 
It  is  decomposed  by  heat,  with  liberation  of  nitrogen  tetroxide. 

SULPHATES. — The  neutral  sulphate,  SO4Pb — is  formed  by  the  action 
of  hot  concentrated  sulphuric  acid  on  lead;  or,  by  double  decomposition 


LEAD.  387 

between  a  sulphate  and  a  lead  salt  in  solution.  It  is  a  white  powder, 
almost  insoluble  in  water;  soluble  in  concentrated  sulphuric  acid,  from 
which  it  is  deposited  on  dilution. 

CHROMATES. — The  neutral  chromate,  CrO4Pb — is  formed  by  precipi- 
tating lead  nitrate  with  potassium  chromate,  and  is  used  as  a  pigment, 
chrome  yellow.  It  is  insoluble  in  water;  soluble  in  alkalies. 

ACETATES. — The  Neutral  acetate — Salt  of  Saturn — Sugar  of  lead— 
Plumbi  acetas — (C2H3O2)2Pb  +  3Aq. — is  prepared  by  dissolving  litharge  in 
acetic  acid;  or,  by  exposing  lead  in  contact  with  acetic  acid  to  the  at- 
mosphere, evaporating  and  crystallizing. 

It  crystallizes  in  large,  oblique,  rhombic  prisms,  sweetish,  with  a  me- 
tallic after-taste;  soluble  in  1.5  parts  cold  water  and  in  8  parts  alcohol. 
The  solutions  are  acid.  By  exposure  to  the  air  it  effloresces  upon  the 
surface  and  is  superficially  converted  into  carbonate.  It  fuses  at  75.5°; 
loses  Aq.  and  a  part  of  its  acid  to  100°,  forming  the  sesquibasic  acetate. 
At  280°  it  enters  into  true  fusion,  and  at  a  slightly  higher  temperature  is 
decomposed  into  carbon  dioxide,  acetone,  and  lead.  Its  aqueous  solution 
dissolves  litharge,  with  formation  of  basic  acetates. 

Of  the  subacetates,  that  having  the  composition  (C2II3O2)PbOH,  2PbO, 
the  sexbasic  acetate,  is  the  only  one  requiring  mention.  It  is  the  main 
constituent  of  Liq.  plumb i  subacetatis  (U.  S.,  Br.),  or  Goulard's  extract, 
obtained  by  boiling  a  solution  of  the  neutral  acetate  with  lead  monoxide 
in  fine  powder.  This  solution  becomes  milky  when  added  to  ordinary 
water,  by  formation  of  lead  sulphate  and  carbonate. 

LEAD  CARBOXATE — Plumbi  carbonas  (U.  S.,  Br.) — CO3Pb — is  formed 
by  double  decomposition  between  a  carbonate  and  a  salt  of  lead  in  solu- 
tion, or  by  passing  carbon  dioxide  through  a  solution  containing  lead. 
It  is  a  white  powder,  sp.  gr.  6.43;  insoluble  in  water. 

Besides  the  neutral  salt  there  exist  several  basic  carbonates  which  occur 
in  varying  proportions  in  the  commercial  product  known  as  ceruse  or 
white  lead.  This  is  prepared  by  several  processes.  In  the  Clichy  process, 
which  is  that  usually  adopted,  litharge  is  dissolved  in  lead  acetate  so- 
lution, and  the  subacetate  thus  produced  is  decomposed  by  a  current  of 
carbon  dioxide,  the  neutral  acetate  being  regenerated  and  used  again. 

White  lead  is  used  in  oil-painting,  forming  apart  of  all  but  the  darkest 
pigments.  The  darkening  of  lead  whites  by  exposure  to  air  is  due  to  the 
presence  of  traces  of  hydrogen  sulphide  in  the  atmosphere.  The  regen- 
eration of  oil-paintings  dimmed  by  atmospheric  action  is  accomplished  by 
oxygenated  water,  which  oxidizes  the  dark  sulphide  to  the  white  sulphate. 

Analytical  characters. — Hydrogen  sulphide  in  acid  solution  ;  a 
black  precipitate,  insoluble  in  acids  and  in  alkaline  sulphides.  Am- 
monium sulphydrate ;  black  precipitate,  insoluble  in  excess.  Hydro- 
chloric acid ;  white  precipitate,  soluble  in  boiling  water,  from  which  it 
crystallizes  on  cooling;  not  altered  in  appearance  by  ammonium  hydrate. 
This  reaction  does  not  occur  in  dilute  solutions.  Ammonium  hydrate  / 
white  precipitate,  insoluble  in  excess.  Potassium  hydrate ;  white  pre- 
cipitate, soluble  in  excess,  especially  when  heated.  Sulphuric  acid  or 
sulphate  /  white  precipitate,  insoluble  in  weak  acids,  soluble  in  solution 
of  ammonium  tartrate.  Potassium  iodide  /  yellow  precipitate,  sparingly 
soluble  in  boiling  water,  soluble  in  a  large  excess  of  the  reagent.  Potas- 
sium chromate ;  yellow  precipitate,  soluble  in  potash  solution.  Iron  or 
zinc  separate  the  element  from  solutions  of  its  salts. 

Action  on  the  economy. — All  of  the  soluble  compounds  of  lead 
and  those  which,  although  not  soluble,  are  readily  convertible  into  solu- 


388  GENERAL    MEDICAL    CHEMISTRY. 

ble  compounds  by  water,  air,  or  the  digestive  fluids,  are  actively  poisonous. 
Some  are  also  injurious  by  their  local  action  upon  the  tissues  with  which  they 
come  in  contact;  such  are  the  acetate,  and,  in  a  less  degree,  the  nitrate. 

The  chronic  form  of  lead  intoxication,  painter's  colic,  etc.,  is  purely 
poisonous,  and  is  produced  by  the  continued  absorption  of  minute  quan- 
tities of  lead,  either  by  the  skin,  lungs,  or  stomach.  The  acute  form  pre- 
sents symptoms  referable  to  the  local  as  well  as  to  the  poisonous  action 
of  the  lead  salt,  and  is  usually  caused  by  ths  ingestion  of  a  single  dose  of 
the  acetate  or  carbonate. 

Metallic  lead,  although  probably  not  poisonous  of  itself,  causes  chronic 
lead-poisoning  by  the  readiness  with  which  it  is  converted  into  com- 
pounds capable  of  absorption.  The  sources  of  poisoning  by  metallic  lead 
are:  the  contamination  of  drinking  water  which  has  been  in  contact  with 
the  metal  (see  p.  56);  the  use  of  articles  of  food  or  of  chewing  tobacco 
which  has  been  packed  in  tin-foil  containing  an  excess  of  lead;  the 
drinking  of  beer  or  other  beverages  which  have  been  in  contact  with 
pewter;  or  the  handling  of  the  metal  and  its  alloys. 

Almost  all  the  compounds  of  lead  may  produce  painter's  colic.  The 
carbonate,  in  painters,  artists,  manufacturers  of  white  lead,  and  in  per- 
sons sleeping  in  newly  painted  rooms;  the  oxides,  in  the  manufacturers  of 
glass,  pottery,  sealing-wax,  and  litharge,  and  by  the  use  of  lead-glazed 
pottery;  by  other  compounds,  by  the  inhalation  of  the  dust  of  cloth  fac- 
tories, and  by  the  use  of  lead  hair-dyes. 

Acute  lead-poisoning  is  by  no  means  of  as  common  occurrence  as  the 
chronic  form,  and  usually  terminates  in  recovery.  It  is  caused  by  the 
ingestion  of  a  single  large  dose  of  the  acetate,  subacetate,  carbonate, 
or  of  red  lead.  In  such  cases  the  administration  of  magnesium  sulphate 
is  indicated;  it  enters  into  double  decomposition  with  the  lead  salt  to 
form  the  insoluble  lead  sulphate. 

Lead  once  absorbed  is  eliminated  very  slowly,  it  becoming  fixed  by 
combination  with  the  albuminoids,  a  form  of  combination  which  is  ren- 
dered soluble  by  potassium  iodide.  The  channels  of  elimination  are  by 
the  perspiration,  urine,  and  bile. 

In  the  analysis  for  mineral  poisons  (see  p.  128),  the  major  part  of 
the  lead  is  precipitated  as  sulphide  in  the  treatment  by  sulphuretted 
hydrogen.  The  lead  sulphide  remains  upon  the  filter  after  extraction 
with  ammonium  sulphydrate;  it  is  treated  with  warm  hydrochloric  acid, 
which  decolorizes  it  by  transforming  the  sulphide  to  chloride.  The  lead 
chloride  thus  formed  is  dissolved  in  hot  water,  from  which  it  crystallizes 
on  cooling.  The  solution  still  contains  lead  chloride  in  sufficient  quantity 
to  respond  to  the  tests  for  the  metal. 

Although  lead  is  not  a  normal  constituent  of  the  body,  the  every-day 
methods  in  which  it  may  be  introduced  into  the  economy,  and  the  slow- 
ness of  its  elimination  are  such  as  to  render  the  greatest  caution  neces- 
sary in  drawing  conclusions  from  the  detection  of  lead  in  the  body  after 
death. 

VI.     BISMUTH   GROUP. 
BISMUTH Bi 210 

This  element  is  usually  classed  along  with  antimony:  by  the  older 
authors  among  the  metals,  and  by  the  more  modern  in  the  phosphorus 
group  of  metalloids.  We  are  led,  however,  to  rank  bismuth  in  our  third 


BISMUTH.  389 

class  and  in  a  group  alone,  because:  1st,  while  the  so-called  salts  of  an- 
timony are  not  salts  of  the  element,  but  of  the  radical  antimonyl  (SbO) , 
bismuth  enters  into  saline  combination,  not  only  in  the  radical  bismuthyl, 
(BiO)',  but  also  as  an  element,  as  in  the  nitrate  (NO3)3Bi;  2d,  while 
the  compounds  of  the  elements  of  the  nitrogen  group  in  which  those 
elements  are  quinquivalent,  are,  as  a  rule,  more  stable  than  those  in 
which  they  are  trivalent,  only  one  compound  of  bismuth  is  known  in 
which  that  element  is  quinquivalent,  and  that  one  is  a  very  unstable 
acid;  3d,  the  hydrates  of  the  nitrogen  group  are  strongly  acid  and  their 
corresponding  salts  are  stable  and  well-defined;  but  those  hydrates  of  bis- 
muth which  are  acid  are  but  feebly  so,  and  the  bismuthates  are  formed 
with  difficulty  and  are  unstable;  4th,  no  hydrogen  compound  of  bismuth 
is  known. 

Bismuth  crystallizes  in  rhombohedra;  has  a  brilliant,  metallic  lustre, 
with  bluish  and  reddish  reflections;  is  hard  and  brittle;  fuses  at  247°;  sp. 
gr.  9.935  when  crystallized,  9.677  when  annealed. 

It  is  only  superficially  oxidized  in  cold  air;  heated  to  redness  in  air, 
it  becomes  coated  with  a  yellow  film  of  oxide.  Pure  water  does  not  act 
on  it,  except  at  a  white  heat;  in  water  containing  carbonic  acid  it  forms 
a  crystalline  subcarbonate.  Chlorine,  bromine,  and  iodine  combine  with  it 
directly.  Hot  sulphuric  acid  dissolves  it  as  sulphate.  Nitric  acid  dis- 
solves it  as  nitrate. 

It  is  usually  contaminated  with  arsenic,  from  which  it  is  best  puri- 
fied by  heating  to  redness  a  mixture  of  powdered  bismuth,  potassium 
carbonate,  soap,  and  charcoal,  under  a  layer  of  charcoal.  After  an  hour 
the  mass  is  cooled;  the  button  is  separated  and  fused  until  its  surface  be- 
gins to  be  coated  with  a  yellowish  brown  oxide. 

Oxides. — Four  oxides  are  known:  Bi2O2,  Bi2O8,  Bi2O4,  Bi2O6. 

BISMUTH  TBIOXIDE — Protoxide — Bismuthi  oxldum  (Br.) — BiaO3 — is 
formed  by  decomposing  a  bismuth  or  bismuthyl  salt  by  an  alkali,  and 
boiling  the  liquid  on  the  precipitate.  It  is  a  pale  yellow,  insoluble  pow- 
der; sp.  gr.  8.2;  fuses  at  a  red  heat.  It  is  reduced  by  hydrogen  or  char- 
coal. It  dissolves  in  hydrochloric  and  nitric  acids,  and  in  fused  potash. 

Hydrates. — Bismuth  forms  at  least  four  hydrates:  Bismuthous  hy- 
drate, Bi"'H3O3,  is  formed  as  a  white  precipitate  when  potash  or  ammonia 
is  added  to  a  cold  solution  of  a  bismuth  salt.  This  hydrate,  when  dried, 
loses  water  and  forms  bismuthyl  hydrate  (BiO)'HO.  Bismuthic  acid, 
(BiO2)'  HO,  is  deposited  as  a  red  powder  when  chlorine  is  passed  through 
a  boiling  solution  of  potash  holding  bismuthous  hydrate  in  suspension. 
Pyrobismuthic  acid,  Bi.207H4,  is  a  dark  brown  powder,  precipitated  from 
solutions  of  bismuth  nitrate  by  potassium  cyanide. 

Salts  of  bismuth. — NITRATE,  (NO3)3Bi — obtained  by  dissolving  bis- 
muth in  nitric  acid  and  crystallizing.  It  crystallizes  with  5  Aq.  in  large, 
colorless  prisms;  at  150°,  or  on  contact  with  water,  it  is  converted  into 
bismuthyl  nitrate;  at  260°,  into  the  trioxide. 

Salts  of  bismuthyl. — They  contain  the  group  (BiO)',  and  are 
formed  from  the  corresponding  bismuth  salt  by  the  action  of  water. 

NITRATE — Snbnitrate  or  Magistery  of  bismuth — Bismuthi  subnitras 
(U.  S.,  Br.) — N03(BiO) — is  formed  by  decomposing  a  solution  of  bismuth 
nitrate  with  a  large  quantity  of  water.  In  its  preparation  for  use  in 
medicine,  measures  must  be  taken  to  separate  arsenic;  in  the  Br.  P. 
process,  the  bismuth  itself  is  purified;  in  the  U.  S.  P.  method,  bismuth 
nitrate  is  decomposed  by  sodium  carbonate;  the  bismuthyl  nitrate  so 
formed  is  washed,  redissolved  in  nitric  acid,  the  solution  slowly  precipi- 


390  GENERAL    MEDICAL    CHEMISTRY. 

tated  with  ammonium  hydrate,  and  the  product  washed.  In  the  latter 
process  it  is  expected  that  the  arsenic  will  be  washed  out  as  sodium 
arsenate,  an  end  seldom  attained  in  practice. 

It  is  a  heavy,  white  powder,  faintly  acid;  when  recently  precipitated, 
water  dissolves  it  in  small  quantity,  but  deposits  it  again  on  standing. 
It  is  decomposed  by  pure  water,  but  not  by  water  containing  -^J-^  ammo- 
nium nitrate.  It  usually  contains  1  Aq.,  which  it  loses  at  100°. 

The  cosmetic  known  as  pearl-white  is  sometimes  this  salt,  sometimes 
bismuthyl  chloride. 

CARBONATE — Bismuthi  subcarbonas  (U.  S.) — Bismuthi  carbonas  (Br.) 
— CO3(BiO)2 — a  white  precipitate,  formed  by  alkaline  carbonates  in  solu- 
tions of  bismuth  nitrate.  Heat  decomposes  it  into  carbon  dioxide  and 
bismuth  trioxide. 

Analytical  characters.  —  Water,  white  precipitate,  even  in  the 
presence  of  tartaric  acid,  but  not  in  presence  of  nitric,  hydrochloric,  or 
sulphuric  acid.  Hydrogen  sulphide,  black  precipitate,  insoluble  in  dilute 
acids  and  in  alkaline  sulphides.  Ammonium  sulphydrate,  black  precipi- 
tate, insoluble  in  excess.  Potash,  soda,  or  ammonium  hydrate,  white  pre- 
cipitate, insoluble  in  excess  and  in  tartaric  acid,  turns  yellow  when  the 
liquid  is  boiled.  Potassium  ferrocyanide,  white  precipitate,  insoluble  in 
hydrochloric  acid.  Potassium  ferricy anide,  yellowish  precipitate,  soluble 
in  hydrochloric  acid.  Infusion  of  galls,  orange  precipitate.  Potassium 
iodide,  brown  precipitate,  soluble  in  excess. 

Action  on  the  economy. — Although  the  medicinal  compounds  of 
bismuth  probably  are  poisonous,  if  taken  in  sufficient  quantity,  the  ill 
effects  ascribed  to  them  are  in  most,  if  not  all  cases,  referable  to  contami- 
nation with  arsenic.  Symptoms  of  arsenical  poisoning  have  not  only  been, 
frequently  observed  when  the  subnitrate  has  been  taken  internally,  but 
also  when  it  has  been  used  as  a  cosmetic. 

When  preparations  of  bismuth  are  administered,  the  alvine  discharges 
contain  bismuth  sulphide  as  a  dark  brown  powder. 


VII.     TIN  GROUP. 
TITANIUM,  Ti.,  50;   Tix,  Sn.,  118;   ZIRCONIUM,  Zr.,  89.6. 

Titanium  and  tin  are  divalent  in  one  series  of  compounds,  SnCla,  and 
quadrivalent  in  another,  SnCl4.  Zirconium,  so  far  as  known,  is  always 
quadrivalent.  Each  of  these  elements  forms  an  acid  (or  salts  correspond- 
ing to  one)  of  the  composition  MO3Ha,  and  a  series  of  oxysalts  of  the 
composition  (NO3)4MiT. 

TIN. 
Stannum Sn 118 

The  only  member  of  this  group  of  practical  interest,  is  obtained  chiefly 
from  a  native  stannic  oxide,  cassiterite  or  tinstone. 

When  required  pure,  commercial  tin  is  dissolved  in  hydrochloric  acid, 
the  solution  filtered  and  evaporated;  the  chloride  dissolved  in  water  and 
decomposed  with  ammonium  carbonate;  the  protoxide  reduced  by  char- 
coal. 


TIN.  391 

Till  is  a  bluish  white  metal,  soft,  malleable,  ductile;  sp.  gr.  7.285 
when  cast,  7.293  when  hammered;  fuses  at  228°;  emits  a  peculiar  sound, 
the  tin  cry,  when  bent. 

Air  affects  it  but  little  at  ordinary  temperatures;  when  heated  in  air 
it  is  oxidized;  more  rapidly  if  alloyed  with  lead.  It  oxidizes  slowly  in 
water,  more  rapidly  in  salt  water;  if  alloyed  with  lead,  that  metal  is  more 
readily  dissolved  by  water  than  when  it  is  pure.  Hydrochloric  acid  dis- 
solves' it  as  stannous  chloride.  Nitric  acid,  in  presence  of  a  small  quan- 
tity of  water,  converts  it  into  metastannic  acid.  Alkaline  solutions  dis- 
solve it  as  metastannates.  Chlorine,  bromine,  iodine,  sulphur,  phos- 
phorus, and  arsenic  combine  with  it  directly. 

It  is  used  in  the  arts  principally  to  protect  iron  or  copper  surfaces 
from  atmospheric  influences.  Tin  plates  are  thin  sheets  of  iron  coated 
with  tin.  Copper  and  iron  vessels  are  tinned,  after  brightening,  by  con- 
tact with  molten  tin.  The  practice  of  using  an  alloy  of  lead  and  tin  in 
tinning  is  to  be  avoided,  as  the  lead,  when  thus  alloyed,  is  readily  dis- 
solved. Tin-foil,  thin  laminae  of  tin,  is  used  to  exclude  air  and  moisture, 
and  in  the  silvering  of  mirrors.  Pewter,  bronze,  bell  metal,  speculum 
metal,  gun  metal,  britannia  metal,  solder  and  Rose's  alloy,  contain  tin. 
The  compounds  of  tin  are  largely  used  in  dyeing. 

Oxides. — Two  oxides  are  known,  SnO  and  SnOa. 

STANNIC  OXIDE — Binoxide  of  tin — SnO2 — exists  in  nature  as  cassite- 
rite,  and  is  formed  when  tin  or  stannous  oxide  is  calcined  in  air.  Under 
the  name  putty  powder  it  is  used  as  a  polishing  material. 

Hydrates. — Stannous  hydrate,  SnH2O2 — is  a  white  precipitate  pro- 
duced by  alkaline  hydrates  and  carbonates  in  a  solution  of  stannous 
chloride.  Stannic  acid,  SnO3H2,  is  formed  by  the  action  of  the  same  re- 
agents on  stannic  chloride.  Metastannic  acid,  SnBOtlHa,  is  a  white,  in- 
soluble powder,  formed  by  acting  on  tin  with  concentrated  nitric  acid. 

Chlorides. — Two  chlorides  of  tin  are  known: 

STANNOUS  CHLORIDE — Protochloride  of  tin — Tin  crystals — SnCl2 — 
is  obtained  by  dissolving  tin  in  hydrochloric  acid.  It  crystallizes  with 
2  Aq.  in  colorless  prisms,  soluble  in  a  small  quantity  of  water,  but  decom- 
posed, with  formation  of  an  oxychloride,  by  a  large  quantity,  unless  hy- 
drochloric acid  be  added.  In  air  it  is  converted  into  stannic  chloride  and 
oxychloride.  Oxidizing  and  chlorinating  agents  convert  it  into  stannic 
chloride.  It  is  a  useful  reducing  agent,  separates  gold  from  its  chloride, 
and  converts  mercuric  chloride  into  mercurous  chloride  and  mercury.  It 
is  used  as  a  mordant  in  dyeing. 

STANNIC  CHLORIDE — Bichloride  of  tin — Liquid  of  Libamus — SnCl4 
— is  formed  from  the  preceding  compound,  or  by  the  action  of  dry  chlo- 
rine on  tin,  as  a  fuming,  yellowish  liquid;  sp.  gr.  2.28;  boils  at  120°. 

Salts. — STANNOUS  NITRATE,  (NO3).2Sn — formed  when  stannous  hy- 
drate is  dissolved  in  nitric  acid.  The  solution  deposits  metastannic  acid. 

STANNIC  NITRATE,  (NO3)4Sn — formed  when  stannic  oxide  is  dissolved 
in  nitric  acid. 

STANNOUS  SULPHATE,  SO4Sn,  and  STANNIC  SULPHATE,  (SO4)2Sn — 
are  produced,  the  former  when  stannous  hydrate  is  dissolved  in  hot  dilute 
sulphuric  acid,  and  the  latter  when  tin  is  dissolved  in  strong  boiling 
sulphuric  acid. 

Analytical  characters. — STANNOUS. — Potash  or  Soda,  white  pre- 
cipitate, soluble  in  excess;  the  solution  deposits  tin  when  boiled.  Am- 
monium hydrate,  white  precipitate,  insoluble  in  excess;  turns  olive-brown 
when  the  liquid  is  boiled,  Hydrogen  sulphide,  dark  brown  precipitate, 


392 


GENERAL    MEDICAL    CHEMISTRY. 


soluble  in  potash,  alkaline  sulphides,  and  hot  hydrochloric  acid.  Mercuric 
chloride,  white  precipitate,  turning  gray  and  black.  Auric  chloride,  pur- 
ple or  brown  precipitate  in  presence  of  a  small  quantity  of  nitric  acid. 
Zinc,  deposit  of  tin. 

STANNIC. — Potash  or  Ammonium  hydrate,  white  precipitate,  soluble 
in  excess.  Hydrogen  sulphide,  yellow  precipitate,  soluble  in  alkalies, 
alkaline  sulphides,  and  hot  hydrochloric  acid.  Sodium  hyposulphite, 
yellow  precipitate,  when  heated; 


VIII.     PLATINUM  GROUP. 
PALLADIUM,  Pd.,  106.5  ;    PLATINUM,  Pt.,  198. 

IX.     RHODIUM  GROUP. 
RHODIUM,  Rh.,  104;   RUTHENIUM,  Ru.,  104;   IRIDIUM,  Ir.,  197.2. 

The  elements  of  these  two  groups,  together  with  osmium,  are  usually 
classed  as  "metals  of  the  platinum  ores."  They  all  form  hydrates  (or 
salts  representing  them)  having  acid  properties.  Osmium  has  been  re- 
moved because  the  relations  existing  between  its  compounds  and  those 
of  molybdenum  and  tungsten  are  much  closer  than  those  which  they  ex- 
hibit to  the  compounds  of  these  groups.  The  separation  of  the  remaining 
platinum  metals  into  two  groups  is  based  upon  resemblances  in  the  com- 
position of  their  compounds,  as  shown  in  the  following  table: 


Chlorides. 
PdCl3.  .PtCl2 . .  !RhCl2. .  .RuCl2  . . 


PdCl4..PtCl4.. 


..RuCl4  ..IrCU   .. 


. . . .  Rh,Cl6 . .  Ru,Cl6 . .  Iro 


Oxidts. 

PdO  .  .PtO    . . .  RhO    .  .RuO    .  .IrO 

.. ...jRh/)3..Ru2Os..Ir2O:) 

PdO2..PtOs  ..  jRh02  ..RuO,  ..IrO. 

.. ...iRhO3  ..RuO3  ..IrO, 


PLATINUM. 


Pt 


198 


Exists  in  nature,  associated  with  the  other  platinum  metals,  gold, 
lead,  and  iron;  the  ores  containing  45  to  86  per  cent,  of  platinum. 

It  is  a  grayish  white  metal,  sp.  gr.  21.1  when  cast,  21.5  when  ham- 
mered; softens  at  a  white  heat;  may  be  welded;  fuses  with  difficulty; 
very  malleable,  ductile,  and  tenacious.  When  obtained  by  heating  the 
double  chloride  of  platinum  and  ammonium  it  forms  a  grayish  mass, 
called  spongy  platinum.  It  is  not  oxidized  by  air  or  oxygen;  combines 
directly  with  chlorine,  phosphorus,  arsenic,  silicon,  sulphur,  and  carbon. 
Aqua  regia  is  the  only  acid  which  dissolves  it.  Platinum  vessels  are  per- 
forated or  deteriorated  when  heated  with  metals,  easily  reducible  metallic 
oxides,  mixtures  capable  of  liberating  chlorine,  and  phosphates,  silicates, 
hydrates,  nitrates,  or  carbonates  of  the  alkaline  metals. 

Platinic  chloride,  PtCl4 — formed  by  dissolving  platinum  in  aqua 
regia.  It  crystallizes  in  very  soluble,  yellow  needles,  whose  solution  is 
valuable  as  a  test  for  ammonium  and  potassium. 


LITHIUM.  393 


CLASS  IV. 

ELEMENTS  WHOSE  OXIDES  UNITE  WITH  WATER  TO  FORM  BASES;  NEVER 
TO  FORM  ACIDS.     WHICH  FORM  OXYSALTS. 

I.  SODIUM  GROUP. 
Alkaline  Metals. 


LITHIUM Li 7 

SODIUM Na 23 

POTASSIUM  .       ..K .  .39 


RUBIDIUM Rb 85.4 

CESIUM Cs 132.6 

SILVER Ag 108. 


Each  of  the  elements  of  this  group  forms  a  single  chloride,  M'Cl,  and 
one  or  more  oxides,  the  most  stable  of  which  has  the  composition  M'2O; 
they  are,  therefor,  univalent.  Their  hydrates,  M'HO,  are  more  or  less 
alkaline  and  have  markedly  basic  characters.  Silver  resembles  the  other 
members  of  the  group  in  chemical  properties,  although  it  does  not  in 
physical  characters. 


LITHIUM. 

Li.. 


A  silver- white  metal;  tarnishes  rapidly  in  air;  is  the  lightest  of  the 
solid  elements;  sp.  gr.  0.589;  fuses  at  180°;  burns  in  air;  decomposes 
water  at  the  ordinary  temperature. 

Oxide,  Li2O — is  a  white  solid,  formed  by  burning  lithium  in  dry 
oxygen.  It  dissolves  slowly  in  water  with  formation  of  the  hydrate, 
LiHO. 

Chloride,  LiCl — crystallizes  in  regular  octahedra;  very  deliquescent; 
forms  a  double  chloride  with  platinic  chloride,  which  is  soluble  in  water 
and  in  alcohol. 

Bromide  —  Lithii  bromidum — LiBr — is  formed  by  decomposing  lith- 
ium sulphate  with  potassium  bromide.  Also  by  saturating  a  solution  of 
hvdrobromic  acid  with  lithium  carbonate.  It  forms  deliquescent  nee- 
dles, which  contain  91.95  percent,  of  bromine. 

Salts. — CARBONATE — Lithii  carbonas  (U.  S.) — CO3Li2 — obtained  by 
fusing  lepidodte,  a  native  silicate,  with  barium  sulphate  and  carbonate 
and  potassium  sulphate;  extracting  with  water,  and  precipitating  with 
sodium  carbonate.  The  product  is  purified  by  repeated  washing  with 
water,  suspension  in  water  through  which  carbon  dioxide  is  passed,  and 
reprecipitation  by  boiling  the  solution.  It  is  soluble  in  water  to  the  ex- 
tent of  1.2  parts  per  100;  5.25  parts  per  100  in  water  containing  carbonic 
acid;  insoluble  in  alcohol.  With  uric  acid  it  forms  lithium  urate  (q.  v.). 

Analytical  characters. — Ammonium  carbonate,  white  precipitate 
in  concentrated  solutions,  never  in  dilute  solutions  or  in  presence  of  large 
quantities  of  ammoniacal  salts.  Sodium  phosphates,  white  precipitate 


394  GENERAL    MEDICAL    CHEMISTRY. 

in  neutral  or  alkaline  solution,  soluble  in  acids  and  in  solutions  of  am- 
moniacal  salts.  It  colors  the  Bunsen  flame  bright  red,  and  has  a  spectrum 
of  two  bright  lines — A=:6705  and  6102. 


SODIUM. 
Natrium ........  Na  7 23.043 

Sodium  is  now  obtained  by  a  process  based  upon  the  reduction  of  the 
carbonate  by  coal.  A  mixture  of  dry  sodium  carbonate,  coal,  and  chalk 
is  heated  to  whiteness  in  iron  retorts,  connected  with  suitable  recipients, 
in  which  the  distilled  metal  is  collected  under  a  layer  of  naphtha. 

It  is  a  silver-white  metal,  is  rapidly  tarnished  in  air,  and  becomes 
coated  with  a  brownish  yellow  layer.  At  ordinary  temperatures  it  is  of 
waxy  consistency;  at  95.6°  it  fuses;  at  a  white  heat  it  volatilizes;  sp.  gr. 
0.972  at  15°. 

In  air  it  is  gradually  oxidized  from  the  surface  inward,  but  may  be 
kept  in  well-closed  vessels  without  the  protection  of  a  layer  of  naphtha. 
It  decomposes  water;  frequently,  if  the  sodium  have  been  long  kept,  with 
an  explosion.  It  burns  with  a  yellow  flame.  Its  affinities  are  the  same 
as,  but  less  active  than,  those  of  potassium. 

Oxides. — Three  oxides  of  sodium  have  been  described,  Na40,  Na20, 
Na202.  The  protoxide,  Na20,  is  a  grayish  white  mass,  formed  when 
sodium  is  burned  in  dry  air,  or  by  action  of  sodium  upon  sodium  hydrate. 

Hydrate — Caustic  soda — Soda  (U.  S.,  Br.)— NaHO— is  formed 
when  water  is  decomposed  by  sodium.  It  is  usually  obtained  by  decom- 
posing the  carbonate  with  caustic  lime  or  baryta.  The  solution  is  decanted 
from  the  earthy  carbonate  and  evaporated  in  a  silver  basin,  in  which  the 
residue  is  fused  and  cast  into  cylindrical  moulds.  It  is  purified  by  solu- 
tion in  alcohol  and  evaporation.  The  soda  by  baryta  is  purer  than  the 
soda  by  lime  •  the  latter  frequently  contains  arsenic. 

It  is  opaque,  white,  fibrous,  brittle,  fusible  below  redness,  sp.  gr.  2.00; 
very  soluble  in  water;  its  solutions,  known  in  the  arts  as  Soda  lye,  and  in 
pharmacy  as  Liq.  sodce  (the  latter  of  sp.  gr.  1.071),  are  intensely  caustic 
and  alkaline.  When  exposed  to  air  it  absorbs  water  and  is  converted 
into  the  carbonate. 

Soda  solutions  attack  glass  very  readily;  the  necks  and  stoppers  of 
bottles  containing  them  should  be  well  coated  with  paraffine. 

Chloride  —  Common  salt  —  Sea  salt —  Table  salt  —  Sodii  chloridum 
(U.  S.,  Br.) — NaCl — occurs  abundantly  in  nature,  deposited  in  the  solid 
form  as  rock  salt,  in  solution  in  all  natural  waters,  in  suspension  in  the 
atmosphere,  and  as  a  constituent  of  almost  all  vegetable  and  animal 
tissues.  It  is  formed  in  an  infinite  variety  of  chemical  reactions.  It  is 
obtained  from  the  natural  deposits  of  rock  salt;  or  by  evaporation  of  sea- 
water  or  the  water  of  saline  springs.  It  is  the  source  from  which  all  the 
compounds  of  sodium  are  industrially  obtained,  directly  or  indirectly. 

It  crystallizes  in.  anhydrous  cubes  or  octahedra;  sp.  gr.  2.078;  fuses 
at  a  red  heat,  and  crystallizes  on  cooling;  at  a  white  heat  it  volatilizes 
sensibly.  One  part  of  the  salt  dissolves  in  2.78  parts  of  water  at  14°; 
in  2.7  parts  at  60°,  and  in  2.48  parts  at  109.7°.  Dilute  solutions,  on  freez- 
ing, yield  pure  ice.  Hydrochloric  acil  precipitates  it  from  its  concen- 
trated solution.  It  is  insoluble  in  absolute  alcohol,  sparingly  soluble 


SODIUM.  395 

in  weak  alcohol.     Sulphuric  acid  decomposes  it  with  formation  of  sodium 
sulphate  and  liberation  of  hydrochloric  acid. 

Physiological.  —  Sodium  chloride  exists  in  every  animal  tissue  and 
fluid,  and  is  present  in  the  latter,  especially  the  blood,  in  tolerably  con- 
stant proportion.  It  is  introduced  with  the  food,  either  as  a  constituent 
of  the  alimentary  substances,  or  as  a  condiment.  In  the  body  it  serves  to 
aid  the  phenomena  of  osmosis  and  to  maintain  the  solution  of  the  albu- 
minoids. It  is  probable,  also,  that  it  is  decomposed  in  the  gastric  mucous 
membrane  with  formation  of  free  hydrochloric  acid. 

It  is  discharged  from  the  economy  by  all  the  channels  of  elimination, 
notably  by  the  urine,  when  the  supply  by  the  food  is  maintained.  If, 
however,  the  food  contain  no  salt,  it  disappears  from  the  urine  before  it 
is  exhausted  from  the  blood. 

The  amount  of  chlorine  (mainly  in  the  form  of  sodium  chloride)  voided 
by  a  normal  male  adult  in  24  hours  is  about  10  grams,  corresponding  to 
16.5  grams  of  sodium  chloride.  When  normal  or  excessive  doses  are  taken, 
the  amount  eliminated  by  the  urine  is  less  than  that  taken  in;  when  small 
quantities  are  taken,  the  elimination  is  at  first  in  excess  of  the  supply. 
The  hourly  elimination  increases  up  to  the  seventh  hour,  when  it  again 
diminishes.  The  amount  of  sodium  chloride  passed  in  the  urine  is  less 
than  the  normal  in  acute,  febrile  diseases;  in  intermittent  fever  it  is  dim- 
inished during  the  paroxysms,  but  not  during  the  intervals.  In  diabetes 
it  is  much  increased,  sometimes  to  29  grams  per  diem. 

Quantitative  determination  of  chlorides  in  urine.—  The  process  is 
based  upon  the  formation  of  the  insoluble  silver  chloride,  and  upon  the 
formation  of  the  brown  silver  chromate  in  neutral  liquids,  in  the  absence 
of  soluble  chlorides.  The  solutions  required  are: 

First.  —  A  solution  of  silver  nitrate  of  known  strength,  made  by  dis- 
solving 29.075  grams  of  pure,  fused  silver  nitrate  (see  p.  407)  in  a  litre  of 
water.  Second.  —  A  solution  of  neutral  potassium,  chromate. 

To  conduct  the  determination,  5  —  10  c.c.  of  the  urine  are  placed  in  a 
platinum  basin,  2  grams  of  sodium  nitrate  (free  from  chloride)  are  added; 
the  whole  is  evaporated  to  dryness  over  the  water-bath,  and  the  residue 
heated  gradually  until  a  colorless,  fused  mass  remains.  This,  on  cooling, 
is  dissolved  in  water,  the  solution  placed  in  a  small  beaker,  treated  with 
pure,  dilute  nitric  acid  to  faintly  acid  reaction,  and  neutralized  with  cal- 
cium carbonate.  Two  or  three  drops  of  the  chromate  solution  are  added, 
and  then  the  silver  solution  from  a  burette,  during  constant  stirring  of 
the  liquid  in  the  beaker,  until  a  faint  reddish  tinge  remains  permanent, 
Each  c.c.  of  the  silver  solution  used  represents  10  milligrams  of  sodium 
choride  (or  6.065  milligrams  of  chlorine)  in  the  amount  of  urine  used. 

Example.  —  5  c.c.   urine  used,  6  c.c.  silver  solution  added;  1,200  c.c. 


urine  passed  in  24  hours:  .-.l  x  1,200=14.4   grams    NaCl    in   24 

5 
hours. 

If  the  urine  contain  iodides  or  bromides,  they  must  be  removed  by 
acidulating  the  solution  of  the  residue  of  incineration  with  sulphuric 
acid,  removing  the  iodine  or  bromine  by  shaking  with  carbon  disulphide, 
neutralizing  the  aqueous  solution  with  calcium  carbonate  and  proceeding 
as  above. 

Bromide,  NaBr.  —  formed  by  dissolving  bromine  in  a  solution  of 
caustic  soda  to  saturation,  evaporating  to  dryness,  calcining  the  residue 
at  a  dull  red  heat;  redissolving  in  water,  filtering  and  crystallizing.  It 
crystallizes  in  anhydrous  cubes;  soluble  in  1.13  parts  of  water  at  20% 


396  GENERAL    MEDICAL    CHEMISTRY. 

and  in  0.87  at  100°;  soluble  in  alcohol.     It  contains  77.67  per  cent,  of 
bromine. 

Iodide,  Nal — prepared  by  heating  together  water,  iron-filings,  and 
iodine  in  line  powder,  filtering,  adding  an  equivalent  quantity  of  sodium 
sulphate  and  some  slacked  lime;  boiling,  decanting,  and  evaporating.  It 
crystallizes  in  anhydrous  cubes;  soluble  in  0.56  parts  of  water  at  20°, 
and  in  0.32  at  100°;  soluble  in  alcohol.  It  contains  84.66  per  cent,  of 
iodine. 

Salts  of  Sodium. — NITRATE —  Cubic  saltpetre —  Chili  saltpetre — Sodii 
nitras  (U.  S.) — NO3Na — occurs  in  natural  deposits  in  Chili  and  Peru.  It 
crystallizes  in  anhydrous  rhombohedra;  is  deliquescent;  has  a  cooling, 
saline,  and  somewhat  bitter  taste;  fuses  at  310°,  and,  when  strongly 
heated,  is  decomposed  with  formation  of  nitrite,  and  then  of  hydrate  of 
sodium  and  nitric  acid;  very  soluble  in  water;  less  soluble  in  water  con- 
taining free  nitric  acid;  sparingly  soluble  in  alcohol. 

It  is  used  in  the  manufacture  of  saltpetre,  in  the  manufacture  of 
nitric  acid,  sodium  sulphate  being  a  byproduct,  and  as  a  fertilizer. 

Sulphates. — There  are  five  sodium  sulphates:  SO.NaH,  SO.Na.,  S 
07Na2,  (S04)2Na3H,  and  (SO4)3NaII3. 

Ilydrosodic  sulphate — Acid  sodium,  sulphate — Sodium  bisidphate — SO4 
NaH — crystallizes  in  long,  four-sided  prisms;  is  unstable,  and  is  decom- 
posed by  exposure  to  air,  by  water  or  by  alcohol,  into  sulphuric  acid  and 
the  neutral  sulphate.  When  heated  to  dull  redness,  it  is  converted  into 
the pyrosulphate,  S2O7Na2,  corresponding  to  pyrosulphuric  or  Nordhau- 
sen  acid. 

Sodic  sulphate — Neutral  sodium,  sulphate — Glauber's  salt — Sodii  sul- 
phas (U.  S.) — Soda?  sulphas  (Br.) — SO4Naa — occurs  in  nature  in  the  solid 
form,  and  in  solution  in  many  natural  waters.  It  is  obtained  as  a  step  in 
the  manufacture  of  the  carbonate  (q.  v.),  from  the  natural  deposits,  from 
the  mother-liquors  of  the  preparation  of  sodium  chloride,  and  as  a  bypro- 
duct in  the  manufacture  of  nitric  acid;  principally  by  the  decomposition 
of  sodium  chloride  by  sulphuric  acid. 

It  crystallizes  with  water  in  two  proportions,  7  Aq.  and  10  Aq.  The 
salt,  SO4Na2-}-7Aq.  is  deposited  from  saturated  or  supersaturated  solutions 
at  +  5°.  The  salt,  S04Na2+10  Aq.  is  that  usually  met  with  and  which 
is  used  in  pharmacy.  It  crystallizes  in  large,  colorless,  oblique,  rhombic 
prisms,  which  effloresce  in  air  and  gradually  lose  all  their  Aq.  It  fuses 
.at  33°  in  its  water  of  crystallization,  and  is  gradually  converted  into  the 
anhydrous  salt.  If  fused  at  33°  and  allowed  to  cool,  it  remains  liquid  in 
.supersaturated  solution,  from  which  it  is  deposited,  the  entire  mass  be- 
coming crystalline  on  contact  with  the  smallest  particle  of  foreign  matter. 
It  is  sparingly  soluble  in  alcohol. 

Physiological. — The  neutral  sulphates  of  sodium  and  potassium  seem 
to  exist  in  small  quantity  in  all  animal  tissues  and  fluids,  with  the  excep- 
tion of  milk,  bile,  and  gastric  juice;  they  certainly  exist  in  the  blood  and 
urine.  They  are  partially  introduced  with  the  food,  and  in  part  formed 
in  the  body  as  a  result  of  the  metamorphosis  of  those  constituents  of  the 
tissues  which  contain  sulphur  in  organic  combination. 

The  principal  elimination  of  the  sulphates  is  by  the  urine.  All  the 
sulphuric  acid  in  the  urine  is  not  in  simple  combination  with  the  alkaline 
metals,  a  considerable  amount  exists  in  the  form  of  the  alkaline  salts  of 
conjugate,  monobasic  ether  acids,  which  on  decomposition  yield  an 
aromatic  organic  compound.  The  amount  of  sulphuric  acid  discharged 
.by  the  urine  in  twenty-four  hours,  in  the  form  of  alkaline  sulphates,  is 


SODIUM.  397 

from  2.5  to  3.5  grams;  that  eliminated  in  the  salts  of  the  conjugate  acids, 
0.617  to  0.094  gram. 

HYPOSULPHITE — Sodii  hi/2)osulphis  (U.  S.) — S2O3Na.,-f-5Aq. — is  ob- 
tained by  fusing  together  sulphur  and  sodium  carbonate  ;  oxidizing  the 
sulphide  so  formed;  dissolving  sulphur  in  the  hot,  concentrated  solution 
of  the  sulphite,  and  crystallizing. 

It  crystallizes  in  large,  colorless  prisms,  which  fuse  at  45°.  One  part 
dissolves  in  1.44  part  of  water  at  20°;  and  in  0.52  part  at  60°.  It  is  in- 
soluble in  alcohol.  Its  solutions  precipitate  alumina  from  its  salts  with- 
out precipitating  iron  or  manganese  ;  they  dissolve  many  compounds 
which  are  insoluble  in  water;  cuprous  hydrate,  iodides  of  lead,  silver,  and 
mercury,  lead  and  calcium  sulphates.  It  acts  as  a  disinfectant,  and  is 
preservative  of  animal  tissues. 

SILICATES. — If  silex  and  sodium  carbonate  be  fused  together,  the 
residue  extracted  with  water  and  the  solution  evaporated,  a  transparent, 
glass-like  mass,  soluble  in  hot  water,  remains  ;  this  is  soluble  glass  or 
water-glass.  W^hen  exposed  to  the  air  in  contact  with  stone,  it  becomes 
entirely  insoluble,  and  is  used  to  render  stone  structures  imperme- 
able. 

PHOSPHATES. — Three  salts  derived  from  orthophosphoric  acid  exist: 

Trisodic  phosphate — Hasic  sodium  phosphate — P04Na3-}-12Aq. — is 
obtained  by  adding  sodium  hydrate  to  disodic  phosphate  and  evaporating 
to  crystallization.  It  crystallizes  in  six-sided  prisms;  soluble  in  5.1  parts 
of  water  at  15.5°.  The  solution  is  alkaline  in  reaction,  and  by  exposure 
to  air  absorbs  carbon  dioxide  with  formation  of  disodic  phosphate,  and 
sodium  carbonate. 

Disodic  phosphate — Hi/drodisodic  phosphate — Neutral  sodium  phos- 
phate — Phosphate  of  soda  —  Sodii  phosphas  (U.  S.)  —  Sodce  phosphas 
(Br.) — P04Na2H-}-12Aq. — is  obtained  by  converting  tricalcic  phosphate 
(bone  phosphate)  into  monocalcic  phosphate,  and  decomposing  that  salt 
with  sodium  carbonate.  It  crystallizes  below  30°  in  oblique,  rhombic  prisms 
with  12  Aq.;  at  33°,  it  crystallizes  with  7  Aq.  The  salt  with  12  Aq. 
effloresces  in  air  and  readily  parts  with  5  Aq.;  it  is  soluble  in  four  parts 
of  cold  water  and  in  two  parts  of  boiling  water;  that  with  7  Aq.  is  not 
efflorescent  and  dissolves  in  eight  parts  of  water  at  23°.  Its  solutions  are 
faintly  alkaline.  It  is  insoluble  in  alcohol. 

Monosodic  phosphate — Acid  sodium  phosphate  —  P04NaH2  -f-  Aq.— 
crystallizes  in  rhombic  prisms.     At  100°  it  loses  its  Aq.,  and,  at  aSout  200° 
is  converted  into  an  acid  pyrophosphate,  P3O7Na2H2,  which  at  204°  is 
converted  into  the  metaphosphate,  P03Na.     It  is  very  soluble  in  water 
and  insoluble  in  alcohol.     Its  solutions  are  acid  in  reaction. 

Physiological. — All  the  sodium  phosphates  exist,  accompanied  by  tho 
corresponding  potassium  salts,  in  the  animal  economy.  The  disodic  and 
dipotassic  phosphates  are  the  most  abundant,  and  of  these  twTo  the  for- 
mer. They  exist  in  every  tissue  and  fluid  of  the  body,  and  are  more 
abundant  in  the  fluids  of  the  carnivora  than  in  those  of  the  herbivom. 
In  the  blood,  in  which  the  sodium  salt  predominates  in  the  plasma,  and 
the  potassium  salt  in  the  corpuscles,  they  serve  to  maintain  an  alkaline 
reaction.  With  strictly  vegetable  diet  the  proportion  of  phosphates  in 
the  blood  diminishes,  and  that  of  the  carbonates  (the  predominating  salts 
in  the  blood  of  the  herbivora)  increases. 

The  monosodic  and  monopotassic  phosphates  exist  in  the  urine,  the 
former  predominating,  and  to  their  presence  the  acid  reaction  of  that 
fluid  is  largely  due.  They  are  produced  by  decomposition  of  the  neutral 


398  GENERAL    MEDICAL    CHEMISTRY. 

salts  by  uric  acid.  The  urine  of  the  herbivora,  whose  blood  is  poor  in 
phosphates,  is  alkaline  in  reaction. 

The  greater  part  of  the  phosphates  in  the  body  are  introduced  with 
the  food;  a  portion  is  formed  in  the  economy  by  the  oxidation  of  phos- 
phorized  organic  substances,  the  lecithins.  (See  p.  286). 

BORATES. — Six  sodium  borates  have  been  described;  the  only  one  re- 
quiring mention  is  Disodic  tetraborate;  Sodium  pyroborate  ;  Borate 
of  sodium;  Jlorax;  Tincal;-  fiodii  borfis  (U.  S.) — Bo4O7Na2-hlOAq. — is 
now  prepared  chiefly  from  the  boracic  acid  of  Tuscany,  which  is  boiled 
with  a  proper  quantity  of  sodium  carbonate  and  crystallized.  It  crystal- 
lizes in  hexagonal  prisms  with  10  Aq.,  or  in  regular  octahedra  with  5  Aq. 
The  former  variety  is  permanent  in  moist  air,  but  effloresces  in  dry  air, 
and  is  soluble  in  12  parts  of  cold  and  in  2  parts  of  boiling  water;  the  lat- 
ter is  permanent  in  dry  air.  Either  form,  when  heated,  fuses  in  its  Aq., 
and  swells  considerably;  at  a  red  heat  it  becomes  anhydrous,  and  on 
cooling  forms  a  clear,  glassy  mass. 

It  is  fatal  to  the  lower  forms  of  animal  life,  and  is  a  safe  and  efficient 
agent  for  driving  off  insect  vermin. 

HYPOCHLOBITE,  ClONa — is  obtained  in  solution  in  the  Liq.  sodcv 
chlorinates  (U.  S.);  Liq.  sodce  chloratce  (Br.);  or  Labarraque's  solution, 
by  decomposing  a  solution  of  chloride  of  lime  (q.  v.)  with  sodium  carbonate 
and  filtering.  It  is  readily  decomposed,  giving  up  a  portion  of  its  chlo- 
rine, which,  being  in  the  nascent  state,  acts  as  an  efficient  decolorizing  and 
disinfecting  agent. 

PERMANGANATE,  MnO4Na — is  prepared  in  the  same  way  as  the  po- 
tassium salt  (q.  v.),  which  it  resembles  in  its  properties.  It  enters  into 
the  composition  of  Condifs  fluid,  and  of  the  disinfectant  known  as  chloro- 
zone,  which  is  a  solution  of  sodium  permanganate  and  hypochlorite. 

ACETATE — Sodiiacetas  (U.  S.) — Sodceacetas  (Br.) — C2H3O2Na+3Aq. 
— is  prepared  by  distilling  purified  calcium  pyrolignite  with  sulphuric 
acid,  neutralizing  with  sodium  carbonate,  and  crystallizing.  It  crystal- 
lizes in  large,  colorless  prisms;  has  a  sharp,  bitterish  taste;  is  soluble  in 
3.9  parts  of  water  at  6°;  soluble  in  alcohol;  in  dry  air  it  loses  3  Aq.,  which 
it  takes  up  again  from  moist  air.  Heated  with  soda-lime,  it  is  decomposed 
with  production  of  marsh-gas.  The  anhydrous  salt,  heated  with  sulphuric 
acid,  yields  glacial  acetic  acid. 

Carbonates. — Three  sodium  carbonates  are  known:  CO3Na2,  CO3Na 
H,(C03)3Na4H2.  Sodium  carbonate — Neutral  carbonate  of  soda — Soda — 
Sal  soda — Washing  soda — Soda  crystals — Sodii  carbonas  (U.  S.) — Sodas 
carbonas  (Br.) — CO3Na2 — is  industrially  the  most  important  of  the  sodium 
compounds,  and  is  manufactured  in  enormous  quantity  from  the  chloride 
by  Leblanc's  or  Solvay's  processes;  or  from  cryolite.,  a  native  fluoride  of 
sodium  and  aluminium. 

Leblanc's  process,  in  its  present  form,  consists  of  three  distinct  pro- 
cesses: First. — The  conversion  of  sodium  chloride  into  the  sulphate  by 
decomposition  by  sulphuric  acid.  Second. — The  conversion  of  the  sul- 
phate into  carbonate  by  heating*  a  mixture  of  the  sulphate  with  calcium 
carbonate  and  charcoal.  The  product  of  this  reaction,  known  as  black 
ball  soda,  is  a  mixture  of  sodium  carbonate  with  charcoal  and  calcium 
sulphide  and  oxide.  Third. — The  purification  of  the  product  obtained  in 
Second.  The  ball  black  is  broken  up,  disintegrated  by  steam,  and  lixivi- 
ated. The  solution,  on  evaporation,  yields  the  soda  salt  or  soda  of  com- 
merce. 

Of  late   years  Leblanc's  process  has  been  in  great  part  replaced  by 


POTASSIUM.  399 

Solvay's  method,  or  ammonia  process,  which  is  more  economical  and 
yields  a  purer  product.  In  this  process  sodium  chloride  and  ammonium 
bicarbonate  react  upon  each  other  with  production  of  the  sparingly  solu- 
ble sodium  bicarbonate  and  the  very  soluble  ammonium  chloride.  The 
sodium  bicarbonate  is  then  simply  collected,  dried,  and  heated,  when  it  is 
decomposed  into  carbonate,  water,  and  carbon  dioxide. 

The  anhydrous  carbonate,  Sodii  carbonas  exsiccata  (U.  S.),  CO3Na2, 
is  formed  as  a  white  powder  by  calcining  the  crystals.  It  fuses  at  dull 
redness  and  gives  off  a  little  carbon  dioxide.  It  combines  with  and  dis- 
solves in  water  with  elevation  of  temperature. 

The  crystalline  sodium  carbonate,  CO3Na24-10Aq.,  forms  large  rhom- 
bic crystals,  which  effloresce  rapidly  in  dry  air;  fuse  in  their  Aq.  at  34°; 
are  soluble  in  water,  most  abundantly  at  38°,  at  which  temperature  100 
parts  of  water  contain  51.67  parts  of  C03Na2.  The  solutions  are  alkaline 
in  reaction. 

Hydrosodic  carbonate — Monosodic  carbonate — Bicarbonate  of  soda — 
Acid  carbonate  of  soda —  Vichy  salt — Sodii  bicarbonas — (U.  S.) — Sodce 
bicarbonas  (Br.) — C03NaH — exists  in  solution  in  many  mineral  waters. 
It  is  obtained  by  the  action  of  carbon  dioxide  upon  the  disodic  salt  in 
the  presence  of  water. 

It  crystallizes  in  rectangular  prisms,  anhydrous  and  permanent  in  dry 
air;  in  damp  air  it  gives  off  carbon  dioxide  and  is  converted  into  the 
sesquicarbonate,  (CO3)3Na4H2.  When  heated  it  gives  off  carbon  dioxide 
and  water,  and  leaves  the  disodic  carbonate;  100  parts  of  water  dissolve 
8.15  parts  at  10°,  and  16.4  parts  at  60°;  above  70°  the  solution  gives  off 
carbon  dioxide.  The  solutions  are  alkaline. 

Physiological. — The  fact  that  the  carbonates  of  sodium  and  potassium 
are  almost  invariably  found  in  the  ash  of  animal  tissues  and  fluids,  is  no 
evidence  of  their  existence  there  in  life,  as  the  carbonates  are  produced 
by  the  incineration  of  the  sodium  and  potassium  salts  of  organic  acids. 
There  is,  however,  excellent  indirect  proof  of  the  existence  of  the  alka- 
line carbonates  in  the  blood,  especially  of  the  herbivora,  in  the  urine  of  the 
herbivora  at  all  times,  and  in  that  of  the  carnivora  and  omnivora  when 
food  rich  in  the  salts  of  the  organic  acids,  with  alkaline  metals,  is  taken. 
The  carbonates  in  the  blood  are  both  the  mono-  and  disodic  and  potassic; 
and  the  carbonic  acid  in  the  plasma  is  held  partially  in  simple  solution, 
and  partly  in  combination  in  the  monometallic  carbonates. 

Analytical  Characters. — Hydrofluosilicic  acid — a  gelatinous  pre- 
cipitate, if  not  too  dilute.  Potassium  pyroantimoniate,  in  neutral  solu- 
tion and  in  the  absence  of  metals  other  than  potassium  and  lithium,  a 
white,  flocculent  precipitate,  becoming  crystalline  on  standing.  Periodic 
acid  in  excess,  a  white  precipitate  if  the  solution  be  not  too  dilute.  The 
Bunsen  flame  is  colored  yellow,  and  shows  a  brilliant  double  line  occupy- 
ing the  position  of  the  D-line  of  the  solar  spectrum;  X=5895  and  5889. 


POTASSIUM. 
Kalium K 39.137 

Is  prepared  by  the  same  process  as  that  used  for  obtaining  sodium.  It 
is  a  silver-white  metal,  brittle  at  0°;  waxy  at  15°;  at  62.5°  it  fuses;  at 
a  red  heat  it  distils  in  green  vapors,  which  condense  in  cubic  crvstals;  sp. 
gr.  0.865  at  15°. 


400  GENERAL    MEDICAL    CHEMISTRY. 

Potassium  is  the  only  metal  which  oxidizes  at  low  temperatures  in  dry 
air,  in  which  it  is  rapidly  coated  with  a  white  layer  of  the  hydrate,  and 
frequently  ignites,  burning  with  a  violet  flame.  It  must  be  kept  under 
naphtha.  It  decomposes  water  or  ice  with  great  energy,  the  reaction 
liberating  heat  enough  to  ignite  the  hydrogen  which  is  set  free.  It  com- 
bines with  chlorine  with  incandescence,  and  also  unites  directly  with  sul- 
phur, phosphorus,  arsenic,  antimony,  and  tin. 

Oxides. — Two  oxides  of  potassium  are  known,  K2O  and  K3O4. 

Hydrate  —  Potash  —  Potassa — Common  caustic — Potassa  (U.  S.) — 
Potassa  caustica  (Br.) — KHO — is  obtained  from  potassium  carbonate  by 
decomposition  with  calcic  hydrate.  The  solution  is  evaporated  and  the 
residue  fused  and  cast  into  cylindrical  moulds;  the  product  is  $)0ta&h  by 
lime.  To  purify  it,  it  is  dissolved  in  alcohol,  the  solution  evaporated,  the 
residue  fused  in  a  silver  basin  and  cast  in  a  silver  mould;  the  product  is 
potash  by  alcohol,  and  is  free  from  potassium  chloride  and  sulphate,  but 
contains  small  quantities  of  the  carbonate,  and  frequently  arsenic. 

It  is  usually  met  with  in  cylindrical  sticks,  hard,  white,  opaque,  and 
brittle.  The  potash  by  alcohol  has  a  bluish  tinge,  and  a  smoother  sur- 
face than  the  common;  sp.  gr.  2.1;  it  fuses  at  dull  redness;  is  freely 
soluble  in  water;  less  so  in  alcohol.  The  solutions  have  a  soapy  taste, 
and  an  alkaline  reaction,  and  are  strongly  caustic.  In  air,  it  absorbs  wa- 
ter and  carbon  dioxide,  and  is  finally  converted  into  the  carbonate.  Its 
solutions  dissolve  chlorine,  bromine,  iodine,  sulphur,  and  phosphorus. 
It  decomposes  the  aimnoniacal  salts  with  liberation  of  ammonia;  arid  the 
salts  of  many  of  the  metals  with  formation  of  a  potassium  salt  and  a 
h}rdrate  of  the  metal.  It  dissolves  the  albuminoids  with  formation  of  an 
alkali  albuminate;  when  heated  with  them,  they  are  decomposed  with 
formation  of  leucin,  tyrosin,  etc.  It  oxidizes  the  carbohydrates  with 
formation  of  potassium  carbonate  and  oxalate. 

Sulphides.— Five  sulphides,  KaS,  K2S2,  K2S3,  KaS4,  and  K2SS,  and  a 
sulphydrate,  KHS,  are  known.  The pentasulphide,  K2S5,  is  formed  when 
excess  of  sulphur  and  potassium  carbonate  are  fused  together;  the  pro- 
duct is  a  brown  mass,  known  as  liver  of  sulphur,  or  Potassii  svlphure- 
tum  (U.  S.);  Potassa  sulphurata  (Br.).  It  is  readily  decomposed,  and 
on  contact  with  hydrochloric  acid  gives  off  hydrogen  sulphide. 

Chloride — Sal  digestivum  Sylvii — KC1 — exists  in  nature,  either  pure 
or  mixed  with  other  chlorides;  at  Stassfurth,  a  double  chloride  of  potas- 
sium and  magnesium,  KC1,  MgCl2  +  6Aq.,  called  carnallite,  is  worked  as  a 
source  of  potassium  compounds. 

It  crystallizes  in  anhydrous  cubes;  permanent  in  air;  100  parts  of  wa- 
ter dissolve  29.23  parts  at  0°,  and  0.2738  part  more  for  every  degree  of 
elevation  of  temperature. 

Bromide — Potassii  bromidum  (U.  S.,  Br:) — KBr — is  formed  either 
by  decomposing  ferrous  bromide  by  potassium  carbonate,  or  by  dissolv- 
ing bromine  in  solution  of  potassium  hydrate.  In  the  latter  case,  a  mix- 
ture of  bromide  and  bromate  is  obtained,  and  the  latter  is  converted  into 
bromide  by  calcining  the  product. 

It  crystallizes  in  anhydrous  cubes  or  tables;  has  a  sharp,  salty  taste; 
is  very  soluble  in  water,  sparingly  so  in  alcohol.  Chlorine  decomposes  it 
with  liberation  of  bromine.  It  contains  67.22  per  cent,  of  bromine. 

Iodide — Potassii  iodidum  (U.  S.,  Br.) — KI — is  obtained  by  satura- 
ting potash  solution  with  iodine,  evaporating,  and  calcining  the  resulting 
mixture  of  iodide  and  iodate  with  charcoal.  The  product  is  very  liable 
to  contain  iodate  and  carbonate. 


POTASSIUM.  401 

It  crystallizes  in  cubes,  which  are  transparent  if  the  iodide  be  pure; 
permanent  in  air,  salty  in  taste;  soluble  to  the  extent  of  100  parts,  in 
73.5  parts  of  water  at  12.5°,  and  in  45  parts  at  120°.  It  dissolves  in  5.5 
parts  of  alcohol  of  sp.  gr.  0.85  at  12.5°.  Chlorine  and  nitrous  and  nitric 
acids  decompose  it  with  liberation  of  iodine.  It  combines  with  many 
other  iodides  to  form  double  iodides. 

Salts.— NITRATE— Nitre — Saltpetre — Potassii  ultras  (U.  S.)-— Potasses 
nitras  (Br.) — NO3K — exists  naturally,  and  is  formed  artificially  as  a  re- 
sult of  the  decomposition  of  nitrogenized  organic  substances.  The  more 
usual  process  for  its  preparation  is  the  decomposition  of  the  native  sodium 
nitrate,  either  by  a  boiling  solution  of  potassium  carbonate,  or  by  potas- 
sium chloride. 

It  crystallizes  in  six-sided,  rhombic  prisms,  which  are  grooved  upon 
the  surface.  It  dissolves  in  water  with  depression  of  temperature,  and 
is  more  soluble  in  water  containing  sodium  chloride;  in  alcohol  it  is  very 
sparingly  soluble.  It  fuses  at  350°,  without  decomposition;  at  a  temper- 
ature below  redness  it  gives  off  oxygen,  and  is  converted  into  the  nitrite, 
NO?K;  when  further  heated  it  is  decomposed  into  nitrogen,  oxygen,  and 
a  mixture  of  the  oxides.  The  readiness  with  which  it  gives  up  its  oxy- 
gen, when  heated  in  presence  of  an  oxidizable  substance,  renders  it  valu- 
able as  an  oxidizing  agent. 

Gunpowder  is  an  intimate  mixture  of  this  salt  with  sulphur  and  car- 
bon, in  such  proportion  that  the  nitre  contains  all  the  oxygen  required  for 
the  combustion. 

CHLORATE — Chlorate  of  potash — Potassii  Moras  (U.  S.) — Potasses 
Moras  (Br.) — C103K — is  prepared  from  potassium  chloride;  this  is  mixed 
with  slaked  lime,  and  the  mixture,  while  heated  to  60°,  treated  with 
chlorine  until  no  further  absorption  of  gas  takes  place,  when  it  is  drawn 
off,  allowed  to  deposit,  the  clear  solution  rapidly  evaporated,  and  the  pro- 
duct purified  by  recrystallization. 

It  crystallizes  in  transparent,  anhydrous  plates.  Soluble  in  water  to 
the  extent  of  6.03  parts  in  100  at  15.37°,  and  24  parts  at  104.7°;  spar- 
ingly soluble  in  weak  alcohol;  fuses  at  400°;  if  further  heated,  it  is  de- 
composed into  chloride  and  perchlorate  with  liberation  of  oxygen,  and  at 
a  still  higher  temperature  the  perchlorate  is  decomposed  into  chloride 
and  oxygen. 

It  is  a  valuable  source  of  oxygen,  and  a  more  active  oxidizing  agent 
than  nitre.  When  mixed  with  readily  oxidizable  substances,  carbon,  sul- 
phur, phosphorus,  sugar,  tannin,  resins,  etc.,  the  mixtures  explode  when 
heated  or  subjected  to  shock,  the  violence  of  the  explosion  being  such  as 
to  prevent  the  use  of  such  mixtures  as  explosives.  With  strong  sul- 
phuric acid,  potassium  chlorate  gives  off  peroxide  of  chlorine,  C1204,  an. 
explosive,  yellowish  gas.  Nitric  acid  decomposes  it  with  formation  of 
nitrate  and  perchlorate,  and  liberation  of  chlorine  and  oxygen.  Heated 
with  hydrochloric  acid,  it  gives  a  mixture  of  chlorine  and  peroxide  of 
chlorine,  the  latter  acting  as  an  energetic  oxidant  in  solutions  in  which 
it  is  generated. 

HYPOCHLORITE,  C1OK — is  formed  in  solution  by  imperfect  saturation 
of  a  cooled  solution  of  potash  with  hypochlorous  acid.  An  impure  solu- 
tion is  used  in  bleaching,  under  the  name  of  Javelle  water. 

SULPHATES. — Two  sulphates,  formed  from  single  molecules  of  the 
acid,  exist,  SO4K2  and  S04KH.  Besides  these,  others  are  known,  such 
as  (SO4)SK4H2,  (SO4)2K3H,  and  the  pyrosulphate,  S,O7K2. 

Sulphate — DipotassiQ  sulphate — Potassii  sulphas — (U.  S.) — Potassoe 
26 


402  GENERAL    MEDICAL    CHEMISTRY. 

sulphas — (Br.) — SO4K0 — exists  in  the  Stassfurth  mines,  in  the  ash  of 
many  plants,  and  in  solution  in  mineral  waters.  It  is  obtained  from  the 
Stassfurth  deposits,  and  as  an  accessory  product  in  many  chemical  manu- 
facturing processes. 

It  crystallizes  in  right  rhombic  prisms;  hard,  permanent  in  air;  salt 
and  bitter  in  taste;  soluble  in  water  to  the  extent  of  10.5  parts  in  100  at 
12°,  and  26.3  parts  at  101.5°. 

Hydropotassic  sulphate-^-Monopotassic  sulphate — Acid  sulphate — 
SO4KH — is  formed  as  a  by-product  infthe  manufacture  of  nitric  acid. 
When  heated  it  loses  water,  and  is  converted  into  the  pyrosulphate, 
S2O7Ka,  which,  at  a  higher  temperature,  is  decomposed  into  the  dipotas- 
sic  salt  and  sulphur  trioxide. 

SULPHITES. — Three  sulphites,  SO3K2,  SOSKH,  and  S2O5K2,  are  known. 

Sulphite — Dipotassic  sulphite — Neutral  potassium  sulphite — Potassii 
sulphis  (U.  S.) — SO3K2 — is  formed  by  saturating  a  solution  of  the  carbo- 
nate with  sulphur  dioxide,  and  evaporating  over  sulphuric  acid.  It  crys- 
tallizes in  oblique  rhombic  octahedra,  which  have  a  sulphurous  odor  and 
are  very  soluble  in  water.  Its  solution,  when  exposed  to  air,  absorbs 
oxygen,  and  the  salt  is  converted  into  the  sulphate. 

GHROMATE — Neutral  chromate — CrO4K2 — is  formed  by  heating  a  mix- 
ture of  chrome  iron  ore,  FeCr2O4,  and  potassium  nitrate  or  carbonate  in 
contact  with  air;  the  residue  is  extracted  with  water;  the  solution  neu- 
tralized with  dilute  sulphuric  acid  and  evaporated.  The  dichromate  thus 
formed  is  dissolved  in  water  and  converted  into  the  chromate  by  neu- 
tralization with  a  suitable  quantity  of  potassium  carbonate. 

BICHROMATE — Bichromate — Potassii  bichromas  (U.  S.) — Potassai 
bichromas  (Br.) — Cr2O7K2 — is  prepared  as  described  above.  It  forms 
large,  reddish  orange  colored,  prismatic  crystals;  soluble  in  water;  fuses 
below  redness,  and  at  a  higher  temperature  is  decomposed  into  oxygen, 
potassium  chromate,  and  sesquioxide  of  chromium.  Hydrochloric  acid 
heated  with  it  gives  off  chlorine. 

PERMANGANATE — Potassii  permanganas  (U.  S.) — Potassce  perman- 
yanas  (Br.) — MnO4K — is  obtained  by  fusing  a  mixture  of  manganese 
dioxide,  potash,  and  potassium  chlorate,  and  evaporating  the  solution  to 
crystallization;  potassium  manganate  and  chloride  are  first  formed;  on 
boiling  with  water  the  manganate  is  decomposed  into  potassium  perman- 
ganate and  hydrate,  and  manganese  dioxide. 

It  crystallizes  in  dark  prisms,  almost  black,  with  greenish  reflections, 
which  yield  a  red  powder  when  broken.  Soluble  in  water,  communicat- 
ing to  it  a  red  color,  even  in  very  dilute  solution.  It  is  a  most  valuable 
oxidizing  agent;  with  organic  matter  its  solution  is  turned  to  green  by 
the  formation  of  the  manganate,  or  deposits  the  brown  sesquioxide  of 
manganese,  according  to  the  nature  of  the  organic  substance;  in  some 
instances  the  reaction  takes  place  best  in  the  cold,  in  others  under  the 
influence  of  heat;  in  some  better  in  acid  solutions,  in  others  in  alkaline 
solutions.  Mineral  reducing  agents  act  more  rapidly.  Its  oxidizing 
powers  render  its  solutions  valuable  as  disinfectants. 

ACETATE — Potassii  acetas  (U.  S.) — Potassce  acetas  (Br.) — C2H3O2K — 
exists  in  the  sap  of  plants;  and  it  is  by  its  calcination  that  the  major  part 
of  the  carbonate  of  wood  ashes  is  formed.  It  is  prepared  by  neutralizing 
acetic  acid  with  carbonate  or  bicarbonate  of  potassium. 

It  forms  crystalline  needles,  deliquescent,  and  very  soluble  in  water; 
less  soluble  in  alcohol.  Its  solutions  a^e  faintly  alkaline. 

CARBONATES. — Dipotassic  carbonate — Salt  of  tartar — Pearlash — Po~ 


POTASSIUM.  403 

tassii  carbonas  (U.  S.) — Potasses  carbonas  (Br.) — CO3K2 — exists  in  min- 
eral waters  and  in  the  animal  economy.  It  is  prepared  industrially  in  an 
impure  form,  known  as  potash  or  pearlash,  from  wood  ashes,  from  the 
molasses  of  beet-sugar,  and  from  the  native  Stassfurth  chloride.  It  is 
obtained  pure  by  decomposing  the  monopotassic  salt,  purified  by  several 
recrystallizations,  by  heat;  or  by  calcining  a  potassium  salt  of  an  organic 
acid.  Thus  cream  of  tartar  mixed  with  nitre  and  heated  to  redness 
yields  a  black  mixture  of  carbon  and  potassium  carbonate,  called  black 
flux;  on  extracting  which  with  water,  a  pure  carbonate,  known  as  salt 
of  tartar,  is  left. 

It  occurs  as  a  white,  granular,  deliquescent  powder;  quite  soluble  in 
water;  insoluble  in  alcohol.  Its  solutions  are  strongly  alkaline. 

Hydropotassic  carbonate — Monopotassic  carbonate — Bicarbonate  of 
potassium — Potassii  bicarbonas  (U.  S.) — Potassce  bicarbonas  (Br.) — CO3 
KH — is  obtained  by  dissolving  the  carbonate  in  water  and  saturating  the 
solution  with  carbon  dioxide.  It  crystallizes  in  oblique  rhombic  prisms, 
much  less  soluble  than  the  carbonate.  In  solution  it  is  gradually  con- 
verted into  the  dipotassic  salt  when  heated,  when  brought  into  a  vacuum, 
or  when  treated  with  an  inert  gas.  The  solutions  are  alkaline  in  reaction 
and  in  taste,  but  are  not  caustic. 

The  substance  used  in  baking,  under  the  name  salceratus,  is  this  or 
the  corresponding  sodium  salt.  Its  extensive  use  in  some  parts  of  the 
country  is  undoubtedly  in  great  measure  the  cause  of  the  prevalence  of 
dyspepsia.  When  used  alone  in  baking  it  "  raises  "  the  bread  by  decom- 
position into  carbon  dioxide  and  dipotassic  (or  disodic)  carbonate,  the 
latter  producing  disturbances  of  digestion  by  its  strong  alkaline  re- 
action. 

OXALATES. — Three  oxalates  are  known:  Potassium  oxalate — Neutral 
oxalate — CQO4K2-f- Aq.,  is  formed  when  oxalic  acid  is  saturated  with  potas- 
sium carbonate.  It  forms  rhombic  prisms,  very  soluble  in  water,  insolu- 
ble in  alcohol.  Hydropotassic  oxalate — Monopotassic  oxalate — Binoxa- 
late  of  potash — C2O4KH.  The  salt  of  sorrel,  or  salt  of  lemon,  is  a  mixture 
of  this  salt  with  the  quadroxalate,  Ca04HK,C2O4H8  +  2Aq.  It  is  used  in 
straw-bleaching  and  for  the  removal  of  ink-stains.  It  closely  resembles 
Epsom  salt  in  appearance,  and  has  been  the  cause  of  many  cases  of  oxalic 
acid  poisoning. 

TARTRATES.  — Potassic  tartrate  —  Dipotassic  tartrate  —  Soluble  tar- 
tar— Neutral  tartrate  of  potash — Potassii  tartras  (U.  S.) — Potassce  tartras 
(Br.) — C4H4O6K2  —  is  prepared  by  neutralizing  the  hydropotassic  salt 
with  potassium  carbonate.  It  forms  a  white,  crystalline  powder,  very 
soluble  in  water,  the  solution  being  dextrogyrous,  [«]D= -4-28.48°;  soluble 
in  240  parts  of  alcohol.  Acids,  even  acetic,  decompose  its  solution  with 
precipitation  of  the  monopotassic  salt. 

Hydropotassic  tartrate — Monopotassic  tartrate —  Cream  of  tartar — 
Potassii  bitartras  (U.  S.) — Potassce  bitartras  (Br.) — C4H406HK.  During 
the  fermentation  of  grape  juice,  as  the  proportion  of  alcohol  increases, 
crystalline  crusts  collect  in  the  cask.  These  constitute  the  crude  tartar  or 
argol  of  commerce,  which  is  composed,  in  great  part,  of  monopotassic  tar- 
trate. The  crude  product  is  purified  by  repeated  crystallization  from 
boiling  water;  digesting  the  purified  tartar  with  hydrochloric  acid  at  20°; 
washing  with  cold  water,  and  crystallizing  from  hot  water. 

It  crystallizes  in  hard,  opaque  (translucent  when  pure),  rhombic  prisms, 
which  have  an  acidulous  taste,  and  are  very  sparingly  soluble  in  water, 
still  less  soluble  in  alcohol.  Its  solution  is  acid,  and  dissolves  many 


404 


GENERAL    MEDICAL    CUEMISTKY. 


metallic  oxides  with  formation  of  double  tartrates.  When  boiled  with 
antimony  trioxide,  it  forms  tartar  emetic. 

It  is  used  in  the  household,  combined  with  monosodic  carbonate,  in 
baking,  the  two  substances  reacting  upon  each  other  to  form  Rochelle 
salt  with  liberation  of  carbon  dioxide. 

Baking-powders  are  now  largely  used  as  substitutes  for  yeast  in  the 
manufacture  of  bread.  Their  action  is  based  upon  the  decomposition  of 
hydrosodic  carbonate  by  sorne  'salt  havjng  an  acid  reaction,  or  by  a  weak 
acid.  In  addition  to  the  bicarbonate  and  flour,  or  corn-starch  (added  to 
render  the  bulk  convenient  to  handle  and  to  diminish  the  rapidity  of  the 
reaction),  they  contain  cream  of  tartar,  tartaric  acid,  alum,  hydrochloric 
acid,  or  acid  phosphates.  Sometimes  ammonium  sesquicarbonate  is  used, 
in  whole  or  in  part,  in  place  of  sodium  carbonate. 

The  reactions  by  which  the  carbon  dioxide  is  liberated  are  the  fol- 
lowing: 


C4H406HK 

Hydropotaseic 
tartrate. 


C03NaH  =  C4H4O6NaK 


Hydrosodic 
carbonate. 


Sodium  potassium 
tartrate. 


HaO 

Water. 


CO, 

Carbon 
dioxide. 


2. 


C4H4O6H2 

Tartaric  acid. 


2C03NaH  =  C4H4O6Na, 


Hydrosodic 
carbonate. 


Disodic  tartrate. 


2H2O 

Water. 


Carbon 
dioxide. 


3.  (SO4)8Al2,SO4Ka  -f  6CO,NaH  =  SO4Ka  +  3S04Naa  +  A12H606  +  6C02. 

Alnmininm  Hydrosodic  Potassic  Sodic  Aluminium          Carbon 

potassium  alum.  carbonate.  sulphate.  sulphate.  hydrate.  dioxide. 


4.  (S04)9Ala 

Aluminium 
sulphate. 


6CO3NaH  =  3SO4Naa  +  A12H6O6 


Hydrosodic 
carbonate. 


Sodic 
sulphate. 


Aluminium 
hydrate. 


6CO, 

Carbon 
dioxide. 


5.  HC1  + 

Hydrochloric 
acid. 


C03NaH  = 

Hydrosodic 
carbonate. 


Nad 

Sodium 
chloride. 


+  H20  +  CO, 

Water.  Carbon 

dioxide. 


6.  PCXNaH,   + 


MonoBOdio 
phosphate. 


C03NaH  =  P04NaaH 


Hydrosodio 
carbonate. 


Disodic. 
phosphate. 


H20 

Water. 


CO, 

Carbon 
dioxide. 


7.  2(S04)3Ala    + 

Aluminium 
sulphate. 


Ammonium 
sesquicarbonate. 


eH,o 

Water. 


=    6SO«(NHJ. 


Ammonium 
sulphate. 


2A12H606  -f 

Aluminium 
hydrate. 


9CO, 

Carbon 
dioxide. 


No.  1  is  the  reaction  which  takes  place  when  cream  of  tartar  and  soda, 
or  a  baking-powder  composed  of  those  substances,  are  used  in  baking. 
The  solid  product  of  the  reaction  is  Rochelle  salt.  No.  2  is  that  which 
occurs  between  tartaric  acid  and  soda,  and  is  but  seldom  utilized.  No.  3 
is  that  between  burnt  potassium  alum  and  soda.  It  is  not  utilized  at . 
present,  as  the  ammonium  alum  is  more  economical.  No.  4  is  that  which 
occurs  in  alum  baking-powders,  the  burnt  ammonia  alum  being  prac- 
tically aluminium  sulphate.  The  solid  residues  of  the  reaction  are  sodic 
sulphate  and  aluminium  hydrate.  No.  5  is  a  reaction  very  little  used, 
owing  to  the  inconvenience  of  handling  a  liquid,  to  the  too  rapid  action 


POTASSIUM.  405 

of  the  substances  upon  each  other,  and  to  the  danger  of  introducing 
arsenic  with  the  acid.  No.  6  is  used  to  a  certain  extent,  and  has  the  ad- 
vantage that  the  solid  residue  of  the  reaction  is  a  normal  constituent  of 
the  body.  No.  7  is  occasionally  utilized  as  an  adjunct  to  No.  3. 

In  our  opinion,  while  yeast  is  to  be  preferred  to  any  baking-powder, 
an  alum-powder  is  in  no  way  more  liable  to  produce  disturbances  of 
digestion  than  one  compounded  of  cream  of  tartar  and  soda.  Referring 
to  Equation  4,  above,  and  taking  the  amount  of  powder  generally  used, 
35  grains  per  pound  of  bread,  it  will  be  seen  that  that  amount  of  powder, 
containing  9.26  grains  of  aluminium  sulphate,  when  neutralized  during 
baking,  produces  11.5  grains  of  Glauber's  salt,  4.24  grains  of  aluminium 
hydrate,  and  7.12  grains  of  carbon  dioxide.  On  the  other  hand,  a  cream 
of  tartar  powder  to  produce,  according  to  reaction  above,  the  same  quan- 
tity, 7.12  grains,  of  carbon  dioxide,  forms  at  the  same  time  33.98  grains  of 
Rochelle  salt.  Assuming  that  one  to  two  pounds  is  the  average  amount  of 
bread  consumed  by  an  adult  in  twenty-four  hours,  there  can  be  but  little 
choice  between  taking  on  the  one  hand  4.24 — 8.48  grains  of  alumina  and 
11.5—23.0  grains  of  Glauber's  salt;  and  on  the  other  hand,  33.98 — 67.96 
grains  of  Rochelle  salt.  Indeed,  there  is  more  danger  to  be  apprehended 
from  the  tendency  of  repeated  small  doses  of  Rochelle  salt  to  render  the 
urine  alkaline  and  thus  favor  the  formation  of  phosphatic  calculi,  than 
from  any  supposed  deleterious  action  of  alumina,  whose  local  action,  even 
in  considerable  doses,  is  that  of  a  very  mild  astringent,  and  whose  ab- 
sorption is  very  doubtful. 

Sodium  potassium  tartrate — Rochelle  salt — Selde  seignette — Potassii  et 
sodiitartras  (U.  S.) — Soda  tartarata  (Br.) — C4H4O6NaK-f-4Aq. — is  pre- 
pared by  saturating  hydropotassic  tartrate  with  sodium  carbonate.  It 
crystallizes  in  large,  transparent  prisms,  which  effloresce  superficially  in 
dry  air  and  attract  moisture  in  damp  air.  It  fuses  at  70 — 80°,  and  loses 
3  Aq.  at  100°.  It  is  soluble  in  water,  the  solutions  being  dextrogyrous, 
[«]D=  +29.67°. 

Potassium  antimonyl  tartrate — Tartarated  antimony — Tartar  emetic — 
Antimonii  et  potassii  tartras  (U.  S.) — Antimonium  tartar atum — (Br.) — 
C4H406K(SbO)' — is  prepared  by  boiling  a  mixture  of  3  parts  antimony  tri- 
oxide  and  4  parts  hydropotassic  tartrate  in  water  for  an  hour,  filtering, 
and  allowing  to  crystallize;  when  required  pure,  it  must  be  made  from 
pure  materials. 

It  crystallizes  in  transparent,  right  rhombic  octohedra,  which  turn 
white  in  air.  It  dissolves  in  19  parts  of  water  at  8.7°,  and  in  2.8°  parts  at 
100°.  Its  solutions  are  acid  in  reaction,  have  a  nauseating,  metallic 
taste,  are  laevogyrous,  [a] D—  -f-  156.2°,  and  are  precipitated  by  alcohol. 
The  crystals  contain  %  Aq.,  which  they  lose  entirely  at  100°,  and  partially 
by  exposure  to  air.  It  is  decomposed  by  the  alkalies,  alkaline  earths, 
and  alkaline  carbonates,  with  precipitation  of  antimony  trioxide.  The 
precipitate  is  redissolved  by  excess  of  soda  or  potash,  or  by  tartaric  acid. 
Hydrochloric,  sulphuric,  and  nitric  acids  precipitate  corresponding  anti- 
monyl compounds  from  solutions  of  tartar  emetic.  It  converts  mercuric 
into  mercurous  chloride.  It  forms  double  tartrates  with  the  tartrates  of 
the  alkaloids. 

CYANIDE,  CNK  or  KCy — is  usually  obtained  from  the  ferrocyanide. 
The  dried  salt  is  mixed  with  dry  potassium  carbonate;  the  mixture  is 
thrown  into  a  red-hot  iron  crucible,  and  heated  as  long  as  effervescence 
continues;  the  fused  mass  is  then  decanted  from  the  precipitated  iron 
and  allowed  to  solidify. 


406  GENERAL    MEDICAL    CHEMISTRY. 

It  is  usually  met  with  in  dull,  white,  amorphous  masses;  odorless 
when  dry,  it  has  the  odor  of  hydrocyanic  acid  when  moist.  It  is  deli- 
quescent, and  very  soluble  in  water;  almost  insoluble  in  alcohol.  Its  solu- 
tion is  acrid,  and  bitter  in  taste,  with  an  after-taste  of  hydrocyanic  acid. 
It  is  very  readily  oxidized  to  the  cyanate,  a  property  which  renders  it 
valuable  as  a  reducing  agent.  Solutions  of  potassium  cyanide  dissolve 
iodine,  silver  chloride,  the  cyanides  of  silver  and  gold,  and  many  metallic 
oxides. 

It  is  actively  poisonous,  and  produces  its  effects  by  decomposition  and 
liberation  of  hydrocyanic  acid  (q.  v.). 

FERROCYANIDE —  Yellow  prussiate  of  potash — Potassiiferrocyanidum 
(U.  S.)— Potassce  prussias  flava  (Br.)— [Fe(CN)6]K4-fc-3Aq.  This  salt, 
the  source  of  the  other  cyanogen  compounds,  is  manufactured  by  adding 
organic  matter  (blood,  bones,  hoofs,  leather,  etc.)  and  iron  to  potassium 
carbonate  in  fusion;  or  by  other  processes  in  which  the  nitrogen  is  ob- 
tained from  the  residues  of  the  purification  of  coal-gas,  from  atmospheric 
air,  or  from  ammoniacal  compounds. 

It  forms  soft,  flexible,  lemon-yellow  crystals,  permanent  in  air  at 
ordinary  temperatures.  They  begin  to  lose  water  at  60°,  and  become 
anhydrous  at  100°.  Soluble  in  2  parts  of  boiling  water,  and  in  4  parts  of 
cold  water;  insoluble  in  alcohol,  which  precipitates  it  from  its  aqueous 
solution.  When  calcined  with  potassium  hydrate  or  carbonate,  potas- 
sium cyanide  and  cyanate  are  formed,  and  iron  is  precipitated.  Heated 
with  dilute  sulphuric  acid,  it  yields  an  insoluble,  white  or  blue  salt,  potas- 
sium sulphate,  and  hydrocyanic  acid.  Its  solutions  form  with  those  of 
many  of  the  metallic  salts,  insoluble  ferrocyanides;  those  of  zinc,  lead 
and  silver  are  white,  cupric  ferrocyanide  is  mahogany-colored,  ferrous  fer- 
rocyanide  is  bluish  white,  ferric  ferrocyanide  (Prussian  blue),  is  dark 
blue.  Blue  ink  is  a  solution  of  Prussian  blue  in  a  solution  of  oxalic  acid. 

FERRICYANIDE — Red  prussiate  of  potash — Fe2(CN)1QK6 — is  prepared 
by  acting  upon  the  ferrocyanide  with  chlorine;  or,  better,  by  heating  the 
white  residue  of  the  action  of  sulphuric  acid  upon  potassium  ferrocyanidc, 
in  the  preparation  of  hydrocyanic  acid,  with  a  mixture  of  1  volume  of 
nitric  acid  and  20  volumes  of  water;  the  blue  product  is  digested  with 
water  and  potassium  ferrocyanide,  the  solution  filtered  and  evaporated. 

It  forms  red,  oblique,  rhombic  prisms,  almost  insoluble  in  alcohol. 
"With  solutions  of  ferrous  salts  it  gives  a  dark  blue  precipitate,  Turn- 
buffs  blue. 

Analytical  characters. — Platinic  chloride  in  the  presence  of  hy- 
drochloric acid,  yellow  precipitate,  crystalline  if  formed  slowly;  sparingly 
soluble  in  water,  much  less  in  alcohol.  Tartaric  acid  in  not  too  dilute 
solution,  white  precipitate,  soluble  in  alkalies  and  concentrated  acids. 
Hydrofluosilicic  acid,  translucent,  gelatinous  precipitate;  forms  slowly, 
soluble  in  potash  and  in  strong  alkalies.  Perchloric  acid,  white  precipi- 
tate, sparingly  soluble  in  water;  insoluble  in  alcohol.  PhospJiomolybdiG 
acid,  white  precipitate;  forms  slowly.  Colors  the  flame  of  the  Bunsen 
burner  violet  (the  color  is  only  observable  in  the  presence  of  sodium 
through  blue  glass),  and  exhibits  two  bright  lines,  one  in  the  red,  one  in 
the  violet:  ^=7680  and  4045. 

Action  of  the  sodium  and  potassium  compounds  upon  the 
economy. — The  hydrates  of  sodium  and  of  potassium,  and  in  a  less  de- 
gree the  carbonates,  disintegrate  animal  tissues,  dead  or  living,  with 
which  they  come  in  contact,  and,  by  virtue  of  this  action,  act  as  power- 
ful caustics  upon  a  living  tissue.  Upon  the  skin  they  produce  a  soapy 


SILVER.  407 

feeling  and  in  the  mouth  a  soapy  taste.  '  Like  the  acids,  they  cause  death, 
either  immediately,  by  corrosion  or  perforation  of  the  stomach;  or  second- 
arily after  weeks  or  months,  by  closure  of  one  or  both  openings  of  the 
stomach,  due  to  thickening  consequent  upon  inflammation. 

The  treatment  consists  in  the  neutralization  of  the  alkali  by  an  acid, 
dilute  vinegar,  or  lemon-juice;  or  by  an  oil,  olive-oil — or  milk,  with  which 
it  forms  a  soap. 

The  other  compounds  of  sodium,  if  the  acid  be  not  poisonous,  are 
without  deleterious  action,  unless  taken  in  excessive  quantity.  Common 
salt  has  produced  paralysis  arid  death  in  a  dose  of  half  a  pound.  The  neu- 
tral salts  of  potassium,  on  the  contrary,  are  by  no  means  without  true 
poisonous  action  when  taken  internally,  or  injected  subcutaneously  in 
sufficient  quantities,  causing  dyspnoaa,  convulsions,  arrest  of  the  heart's 
action,  and  death.  In  the  adult  human  subject,  death  has  followed  the 
ingestion  of  doses  of  |  ss. —  §  j.  of  the  nitrate,  in  several  instances;  doses 
of  3  ij. —  3  ij.  of  the  sulphate,  have  also  proved  fatal. 


SILVER. 
Argentum Ag 107.93 

Although  silver  is  usually  classed  with  the  "  noble  metals,"  it  differs 
from  gold  and  platinum  widely  in  its  chemical  characters,  in  which  it 
closely  resembles  the  alkaline  metals. 

When  pure  silver  is  required,  coin  silver  is  dissolved  in  nitric  acid  and 
the  diluted  solution  precipitated  with  hydrochloric  acid.  The  silver 
chloride  is  washed  until  the  washings  no  longer  precipitate  with  silver 
nitrate;  and  reduced  either:  1st,  by  suspending  it  in  dilute  sulphuric 
acid  in  a  platinum  basin,  with  a  bar  of  pure  zinc,  and  washing  thoroughly 
after  complete  reduction;  or,  2d,  by  mixing  it  with  chalk  and  charcoal 
(AgCl,  100  parts,  C,  5  parts,  Co3Ca,  70  parts)  and  gradually  introduc- 
ing the  mixture  into  a  red-hot  crucible. 

Silver  is  a  white  metal;  sp.  gr.  10.47 — 10.54;  fusible  at  1000°;  very 
malleable  and  ductile;  the  best  known  conductor  of  heat  and  electricity. 
It  is  not  acted  on  by  pure  air,  but  is  blackened  in  air  containing  a  trace 
of  hydrogen  sulphide.  Chlorine,  bromine,  iodine,  sulphur,  selenium,  phos- 
phorus, and  arsenic  combine  with  it  directly.  Hot  sulphuric  acid  dis- 
solves it  as  sulphate,  and  nitric  acid  as  nitrate.  The  caustic  alkalies  do 
not  affect  it.  It  alloys  readily  with  many  metals;  its  alloy  with  copper 
is  harder  than  the  pure  metal. 

Oxides. — Three  oxides  of  silver  are  known:  Ag4O,  Ag2O,  and  Ag2O0. 

Silver  monoxide — Protoxide — Argenti  oxidum   (U.  S.,  Br.) — Ag26 
— formed  by  precipitating  a  solution  of  silver  nitrate  with  potash.     It  is 
a  brownish  powder;  faintly  alkaline  and  very  slightly  soluble  in  water; 
strongly  basic.     It  readily  gives  up  its  oxygen.     On  contact  with  ammo-, 
nium  hydrate  it  forms  a  fulminating  powder. 

Chloride,  AgCl — formed  when  hydrochloric  acid  or  a  chloride  is 
added  to  a  solution  containing  silver.  It  is  white;  turns  violet  and  black 
in  sunlight;  volatilizes  at  260°;  sparingly  soluble  in  hydrochloric  acid; 
soluble  in  solutions  of  the  alkaline  chlorides,  hyposulphites,  and  cyanides, 
and  in  ammonium  hydrate. 

Bromide,  AgBr,  and  Iodide,  Agl — are  yellowish  precipitates,  formed 
by  decomposing  silver  nitrate  with  potassium  bromide  and  iodide. 


408  GENERAL   MEDICAL   CHEMISTRY. 

Salts. — NITRATE — Argenti  ultras  (U.  S.,  Br.) — NO3Ag — is  prepared 
by  dissolving  silver  in  nitric  acid,  evaporating,  fusing,  and  recrystallizing. 
It  crystallizes  in  anhydrous,  right  rhombic  plates;  soluble  in  one  part  of 
cold  water,  in  0.5  part  of  boiling  water.  The  solutions  are  colorless  and 
neutral.  In  the  presence  of  organic  matter  it  turns  black.  The  fused 
salt,  cast  into  cylindrical  moulds,  furnishes  the  Argenti  nitras  fusa  (U.  S.), 
lapis  infernalis,  or  lunar  caustic  of  pharmacy.  If,  during  fusion,  the  tem- 
perature be  raised  too  high,  it, is  first  Decomposed  into  nitrite,  oxygen, 
and  silver,  and,  finally,  leaves  pure  silver. 

Dry  chlorine  and  iodine  decompose  it  with  liberation  of  anhydrous 
nitric  acid.  It  absorbs  ammonia  to  form  a  white  substance,  NO3Ag, 
3NH3,  which,  when  heated,  gives  up  its  ammonia.  Its  solution  is  decom- 
posed very  slowly  by  pure  hydrogen,  with  deposition  of  silver. 

Silver  nitrate  is  used  in  photography,  in  the  manufacture  of  hair- 
dyes,  and  of  marking-ink,  and  in  the  silvering  of  glass. 

CYANIDE — Argenti  cyanidum  (U.  S.) — AgCN — is  prepared  by  pass- 
ing hydrocyanic  acid  through  a  solution  of  silver  nitrate.  It  is  a  white, 
tasteless  powder;  gradually  turns  brown  on  exposure  to  light;  insoluble 
in  dilute  acids;  soluble  in  ammonium  hydrate,  and  in  solutions  of  ammo- 
niacal  salts,  cyanides,  and  of  sodium  hyposulphite.  The  mineral  acids 
decompose  it  with  liberation  of  hydrocyanic  acid. 

Analytical  Characters. — Hydrochloric  acid,  white,  flocculent  pre- 
cipitate, insoluble  in  nitric  acid,  readily  soluble  in  ammonium  hydrate. 
Potash  or  soda,  brown  precipitate,  insoluble  in  excess,  soluble  in  ammo- 
nium hydrate.  Ammonium  hydrate,  from  neutral  solutions,  brown 
precipitate,  soluble  in  excess.  Hydrogen  sulphide  or  ammonium  sulphy- 
drate,  black  precipitate,  insoluble  in  the  last-named  reagent.  Potassium 
bromide,  yellowish  white  precipitate,  insoluble  in  acids,  if  not  very 
abundant,  soluble  in  ammonium  hydrate.  Potassium  iodide,  same  as 
bromide,  but  less  soluble  in  ammonium  hydrate. 

Action  on  the  economy. — Silver  nitrate  acts  both  locally  as  a  cor- 
rosive, and  systematically  as  a  true  poison.  Its  local  action  is  due  to  its 
decomposition  by  contact  with  organic  substances,  resulting  in  the  separa- 
tion of  elementary  silver,  whose  deposition  causes  a  black  stain,  and  libera- 
tion^of  free  nitric  acid,  which  acts  as  a  caustic.  When  absorbed,  it  causes 
nervous  symptoms,  referable  to  its  poisonous  action.  The  blue  coloration 
of  the  skin,  observed  in  those  to  whom  it  is  administered  for  some  time, 
is  due  to  the  reduction  of  the  metal  under  the  combined  influence  of  light 
and  organic  matter;  especially  of  the  latter,  as  the  darkening  is  observed, 
although  it  is  less  intense,  in  internal  organs. 

In  acute  poisoning  by  silver  nitrate,  sodium  chloride  or  white  of  egg 
should  be  given ;  and,  if  the  case  be  seen  before  the  symptoms  of  corrosion 
are  far  advanced,  emetics. 


AMMONIUM  COMPOUNDS. 
Ammonium (NH4) 

Although  the  radical  ammonium  has  probably  never  been  isolated, 
there  can  remain  but  little  doubt  that  such  a  radical  exists  in  combination 
in  the  ammoniacal  compounds.  The  ammonium  hypothesis  is  based  upon 
the  following  facts:  1st,  when  ammonia  ^as  comes  in  contact  with  an  acid 
gas,  the  two  unite,  without  liberation  of  hydrogen,  to  form  an  ammoni- 


AMMONIUM    COMPOUNDS.  409 

acal  salt;  2d,  the  diatomic  anhydrides  unite  directly  with  dry  ammonia, 
with  formation  of  the  ammonium  salt  of  an  amido-acid: 

S03          +      2NH,    =     S03(NH2)(NH4) 

Sulphur  trioxide.  Ammonia.  Ammonium  sulphamate. 

3d,  when  solutions  of  the  ammoniacal  salts  are  subjected  to  electrolysis,  a 
mixture  having  the  composition  NH3-f-H  is  given  off  at  the  negative  pole; 
4th,  amalgam  of  sodium,  in  contact  with  a  concentrated  solution  of  am- 
monium chloride,  increases  much  in  volume,  and  is  converted  into  a  light, 
soft  mass,  having  the  lustre  of  mercury.  This  ammonium  amalgam  is 
decomposed  gradually,  giving  off  ammonia  and  hydrogen  in  the  propor- 
tion NH3  +  H;  5th,  if  the  gases  NH3-hH,  given  off  by  decomposition  of 
the  amalgam,  exist  there  in  simple  solution,  the  liberated  hydrogen 
would  have  the  ordinary  properties  of  that  element;  if,  on  the  other  hand, 
they  exist  in  combination,  the  hydrogen  would  exhibit  the  more  energetic 
affinities  of  an  element  in  the  nascent  state.  The  hydrogen  so  liberated 
is  in  the  nascent  state. 

Oxide  and  Hydrate. — Neither  the  oxide  of  ammonium  (NH4)2O, 
nor  its  hydrate,  NH4HO,  has  as  yet  been  isolated,  both  being  probably 
decomposed  into  ammonia  and  water  immediately  they  are  liberated. 

The  hydrate,  NH4HO — is  considered  as  existing  in  the  so-called  aque- 
ous solutions  of  ammonia,  which  are  clear  liquids,  lighter  than  water, 
have  the  taste  and  odor  of  ammonia,  and  are  strongly  alkaline  in  reac- 
tion. The  Aqua  ammonia?  fortior  (U.  S.)  is  of  sp.  gr.  0.900,  and  con- 
tains 249.5  grams  NH3  per  litre;  that  of  the  British  Pharmacopoaia  is  of 
sp.  gr.  0.891,  and  contains  277  grams  NH3  per  litre.  The  Aqua  am- 
monice  (U.  S.)  is  of  sp.  gr.  0.960,  and  contains  93.1  grams  NH3  per  litre; 
that  of  the  British  Pharmacoposia  is  of  sp.  gr.  0.950,  and  contains  118.0 
grams  NH3  per  litre. 

Sulphides. — Ammonium  forms  four  sulphides  (NH4)2S,  (NH4)2S2, 
(NH4)2S4,  and  (NH4)2S5;  and  a  sulphydrate  (NHJHS. 

The  sulphydrate,  NH4HS — is  formed  in  solution,  for  use  as  a  reagent 
in  analysis,  by  saturating  an  aqueous  solution  of  ammonium  hydrate,  pro- 
tected from  air,  with  hydrogen  sulphide. 

The  sulphides  of  ammonium  are  also  formed  during  the  decomposition 
of  nitrogenous  organic  substances,  and  exist  in  the  gases  discharged 
from  burial-vaults,  sewers,  etc. 

Chloride — Muriate  of  ammonia — Sal-ammoniac — Ammonii  chlori- 
dum  (U.  S.,  Br.) — NH4C1 — is  obtained  from  the  ammoniacal  water  of 
gas-works,  which  contains  ammonium  carbonate  and  tarry  substances.  It 
is  a  translucid,  fibrous,  and  elastic  solid,  salty  in  taste  and  neutral  in  re- 
action; volatilizes  without  fusion  and  without  decomposition;  100  parts 
of  water  dissolve  37.28  parts  of  the  salt  at  20°,  and  77.S4  parts  at  110°. 
Its  solutions  are  neutral,  but  lose  ammonia  and  become  acid  when  boiled. 

Ammonium  chloride  exists  in  minute  quantities  in  the  gastric  juice  of 
the  sheep  and  dog.  It  has  also  been  said  to  occur  in  the  perspiration, 
urine,  saliva,  and  tears,  which  contain  some  ammonium  compound  in 
small  quantity,  but  whether  it  is  the  chloride  or  another  is  not  determined 
with  certainty. 

Bromide — Ammonii  bromidum  (U.  S.,  Br.),  NH4  (Br.) — is  formed 
either  by  combining  ammonia  and  hydrobromic  acid;  or  by  decomposing 
ferrous  bromide  with  aqua  ammonia?;  or  by  double  decomposition  be- 
tween potassium  bromide  and  ammonium  sulphate.  It  is  a  white,  granu- 


410  GENERAL    MEDICAL    CHEMISTRY. 

lar  powder,  or  in  large  prisms,  which  turn  yellow  on  exposure  to  air; 
soluble  in  1.29  parts  of  water.  It  volatilizes  without  decomposition.  It 
contains  81.63  per  cent,  of  bromine. 

Iodide — Ammonii  iodidum  (U.  S.),  NH4I — is  formed  by  the  union 
of  equal  volumes  of  ammonia  and  hydriodic  acid,  or  by  double  decom- 
position of  potassium  iodide  and  ammonium  sulphate.  It  crystallizes  in 
cubes;  deliquescent;  soluble  in  0.60  parts  of  water.  It  contains  87.58  per 
cent,  of  iodine. 

Salts  of  ammonium. — NITRATE — Ammonii  nitras  (U.  S.) — N03 
(NH4) — is  prepared  by  neutralizing  nitric  acid  with  ammonium  hydrate 
or  carbonate.  It  forms  flexible,  anhydrous,  six-sided  prisms;  soluble  in 
0.5  parts  of  water  at  18°;  fuses  at  150°,  and  decomposes  at  210°  with 
formation  of  nitrous  oxide:  N03  (NH4)  =  N20  +  2H2O.  Ammonia  and  nitro- 
gen di-  and  tetroxides  are  also  formed  if  the  heat  be  suddenly  applied  or 
allowed  to  rise  too  high.  ^When  fused  it  is  an  active  oxidant. 

SULPHATES.  —  Ammonic  sulphate  —  Diammonic  sulphate  —  Neutral 
ammonium  sulphate — Ammonii  sulphas  (U.  S.) — SO4(NH4)2 — is  manufac- 
tured from  the  ammoniacal  gas  liquids.  These  are  distilled  with  milk  of 
lime,  and  the  product  directed  into  dilute  sulphuric  acid;  or  the  crude 
liquid  is  passed  through  filters  charged  with  gypsum,  when  calcium  car- 
bonate and  ammonium  sulphate  are  formed.  It  forms  anhydrous  rhombic 
crystals,  quite  soluble  in  water;  fuses  at  140°,  and  is  decomposed  at  200° 
into  ammonia  and  mono-ammonic  sulphate. 

Hydro-ammonic  sulphate — Mono-ammonic  sulphate — Bisulphate  oj 
ammonia,  S04H(NH4) — is  formed  by  the  action  of  sulphuric  acid  upon 
diammonic  sulphate.  It  crystallizes  in  right  rhombic  prisms,  soluble  in 
water  and  in  alcohol. 

ACETATE — 02H302(NH4) — is  formed  by  saturating  acetic  acid  with 
ammonia,  or  with  ammonium  carbonate.  It  is  white,  odorless,  very  solu^ 
ble  in  water  and  in  alcohol;  fuses  at  86°,  and  gives  off  ammonia,  then 
acetic  acid,  and  finally  acetamide.  Its  aqueous  solution  is  used  in  medi- 
cine under  the  names  Liq.  ammonii  acetatis  ;  Spirit  of  Minder erus. 

CARBONATES. — Ammonic  carbonate — Diammonic  carbonate — Neutral 
ammonium  carbonate,  CO3(NH4)2  + Aq. — has  recently  been  prepared  as 
a  crystalline  solid.  When  exposed  to  air  it  is  decomposed  into  ammonia 
and  the  monoammonic  salt. 

Hydroammonic  carbonate — Monoammonic  carbonate — Acid  carbo- 
nate of  ammonia,  C03H(NH4) — is  prepared  by  saturating  a  solution  of 
ammonium  hydrate  or  sesquicarbonate  with  carbon  dioxide.  It  crystal- 
lizes in  large,  rhombic  prisms;  soluble  to  the  extent  of  21  parts  in  100 
in  water  at  20°;  at  60°  it  is  decomposed  into  ammonia  and  carbon  di- 
oxide. 

Ammonium  sesquicarbonate — Sal  volatile — Ammonii  carbonas  (U.  S.) 
— Ammonia  carbonas  (Br.) — (CO3)3(NH4)4H2-hAq. — the  commercial  car- 
bonate of  ammonia,  prepared  by  heating  a  mixture  of  ammonium  chloride 
and  chalk,  and  condensing  the  product;  crystallizes  in  rhombic  prisms; 
has  an  ammoniacal  odor  and  an  alkaline  reaction;  soluble  to  the  extent  of 
25  parts  in  100  of  water  at  13°.  By  exposure  to  air  or  by  heating  its  solu- 
tion, it  is  decomposed  into  water,  ammonia,  and  monoammonic  carbonate. 

Analytical  characters. — The  compounds  of  ammonium  are  odorless 
and  entirely  volatile  at  moderately  elevated  temperatures.  Heated  with 
potash,  they  give  off  ammonia,  recognizable,  1st,  by  changing  moist,  red 
litmus  paper  blue;  2d,  by  its  odor;  and,  3d,  by  forming  white  clouds  on 
contact  with  a  glass  rod  moistened  with  hydrochloric  acid. 


.      CALCIUM.  411  ' 

With  platinic  chloride,  a  yellow,  crystalline  precipitate.  AVith  hy- 
drosodic  tartrate  in  moderately  concentrated  and  neutral  solutions,  a 
white,  crystalline  precipitate. 

Action  on  the  Economy. — Solutions  of  the  hydrate  and  carbonate 
act  upon  animal  tissues  in  the  same  way  as  do  the  corresponding  potas- 
sium and  sodium  compounds.  They,  moreover,  disengage  gaseous  am- 
monia, which  rapidly  causes  intense  dyspnoea,  irritation  of  the  air-passa- 
ges, and  suffocation. 

The  treatment  indicated  is  the  neutralization  of  the  alkali  by  a  dilute 
acid.  Usually  the  vapor  of  acetic  acid  or  of  dilute  hydrochloric  acid 
rnust  be  administered  by  inhalation. 


III.     CALCIUM   GROUP. 

Metals  of  the  Alkaline  Earths. 

CALCIUM,  Ca,  40;  STRONTIUM,  Sr,  87.5;  BARIUM,  Ba,  137.2. 

The  members  of  this  group  are  divalent  in  all  their  compounds;  each 
forms  two  oxides,  MO  and  M0a;  each  forms  a  hydrate  possessed  of  well- 
marked  basic  properties. 

CALCIUM. 
Ca 40 

Calcium  is  a  light  yellow  metal;  hard,  very  ductile;  fusible  at  a  red 
heat;  not  sensibly  volatile;  sp.  gr.  1.984.  It  is  not  altered  in  dry  air,  but 
is  converted  into  the  hydrate  in  moist  air. 

Oxides. —  Calcium  protoxide —  Quick-lime —  Calx  (U.  S.,  Br.) — CaO — 
is  prepared  industrially  by  heating  a  natural  calcium  carbonate;  when 
required  pure,  by  heating  a  carbonate,  obtained  by  precipitation. 

It  occurs  in  white  or  grayish,  amorphous  masses,  odorless,  alkaline 
and  caustic;  sp.  gr.  2.3;  almost  infusible.  With  water,  it  is  converted 
into  the  hydrate;  the  union  is  attended  with  great  elevation  of  tempera- 
ture, and  is  known  as  slaking.  In  air,  lime  becomes  air-slaked,  and  is 
converted  into  a  white  powder,  a  hydrocarbonate,  C03Ca,CaH2O2. 

Calcium  hydrate — Slacked  lime — Calcis  hydras  (Br.) — CaIl2O2 — is 
prepared  by  the  action  of  water  upon  quick-lime.  If  the  quantity  of 
water  used  be  one-third  that  of  the  oxide,  the  hydrate  is  formed  as  a 
dry,  white  powder,  odorless,  alkaline  in  taste  and  reaction.  It  is  more 
soluble  in  cold  than  in  hot  water. 

Lime-water — Liquor  calcis  (U.  S.,  Br.) — is  a  solution  of  the  hydrate 
in  water.  The  solubility  of  calcium  hydrate  is  diminished  by  the  alka- 
lies, and  is  increased  by  sugar  and  mannite.  The  Liq.  calcis  saccharatus 
(Br.)  is  a  solution  of  the  hydrate,  or  of  calcium  saccharate,  in  solution  of 
cane-sugar.  Milk  of  lime  is  lime-water  with  an  excess  of  hydrate.  Cal- 
cium hydrate  absorbs  carbon  dioxide. 

Chloride — Calcii  chloridum  (U.  S.,  Br.) — CaCl2  +  6Aq. — is  obtained 
by  dissolving  marble  in  hydrochloric  acid;  is  a  bitter  substance;  deliques- 
cent and  very  soluble  in  water;  when  fused  it  loses  all  its  Aq.  and 
forms  a  white,  amorphous  mass;  used  as  a  drying  agent. 


412  GENERAL    MEDICAL    CHEMISTRY. 

Chloride  of  lime — Bleaching -powder — Calx  chlorinata  (U.  S.) — 
Calx  chlorata  (Br.) — is  a  mixture  composed  principally  of  calcium  chlo- 
ride, CaCl2,  and  hypochlorite,  (ClO)2Ca;  prepared  by  passing  chlorine 
over  slaked  lime  maintained  in  excess.  It  is  a  grayish  white  powder, 
having  a  bitter,  acrid  taste;  soluble  in  cold  water;  decomposed  by  boiling 
water;  readily  decomposed,  with  liberation  of  chlorine,  by  the  weakest 
acids;  carbon  dioxide  decomposes  it  with  formation  of  calcium  carbonate 
and  liberation  of  hypochlorous  .acid,  i£  it  be  moist;  or  of  chlorine,  if  it 
be  dry. 

Salts. — SULPHATE,  S04Ca. — The  hydrated  compound,  SO4Ca-f2Aq., 
occurs  as  gypsum,  in  right  rhombic  prisms;  frequently  grouped  in  arrow- 
head shaped  macles;  sparingly  soluble  in  water;  more  soluble  in  water 
containing  free  acid  or  chlorides;  insoluble  in  alcohol.  Ground  gypsum 
is  used  in  the  arts  under  the  name  terra  alba.  At  80°,  or  more  rapidly 
between  120°  and  130°,  it  loses  its  Aq.  and  is  converted  into  an  opaque, 
white  mass,  which,  when  ground,  is  plaster-of- Paris. 

The  setting  of  plaster  when  mixed  with  water  is  caused  by  the  con- 
version of  the  anhydrous  into  the  crystalline,  hydrated  salt.  Plaster  sur- 
faces are  rendered  smooth,  dense,  and  capable  of  taking  a  high  polish  by 
adding  glue  and  alum,  or  an  alkaline  silicate,  to  the  water. 

PHOSPHATES. — Three  phosphates  of  calcium  are  known:  (P04)2Ca3, 
(PO.HXCa,,  and  (PO.H^Ca. 

Tricalcic  phosphate — Tribasic  or  neutral  phosphate — Hone  phosphate 
—  Calcis  phosphas  prcecipitata  (U.  S.) — Calais  phosphas  (Br.) — (PO4)3 
Ca3 — This  salt  occurs  in  soils,  in  coprolites,  in  guano,  in  all  plants,  and 
in  every  tissue  and  fluid  of  animal  bodies.  It  is  obtained  by  dissolving 
bone-ash  in  hydrochloric  acid,  filtering,  and  precipitating  with  ammonium 
hydrate;  or  by  double  decomposition  between  calcium  chloride  and  an 
alkaline  phosphate.  When  freshly  precipitated  it  is  gelatinous;  when 
dry,  it  is  a  light,  white,  amorphous  powder;  almost  insoluble  in  pure 
water;  soluble  to  a  slight  extent  in  water  containing  ammoniacal  salts, 
or  chloride  or  nitrate  of  sodium;  readily  soluble  in  dilute  acids,  even  in 
water  charged  with  carbon  dioxide.  Sulphuric  acid  decomposes  it  into 
calcium  sulphate  and  monocalcic  phosphate.  Bone-ash  is  an  impure  tri- 
calcic  phosphate,  used  in  the  manufacture  of  phosphorus  and  of  super- 
phosphate (see  below). 

JDicalcic phosphate,  (P04H)2Ca2+2H2O — a  crystalline,  insoluble  salt; 
formed  by  double  decomposition  between  calcium  chloride  and  disodic 
phosphate  in  acid  solution. 

Monocalcic  phosphate — Acid  calcium  phosphate — Superphosphate  of 
lime — (PO4H2)2Ca — exists  in  brain-tissue  and  in  acid  animal  fluids.  It  is 
formed  when  the  tricalcic  salt  is  dissolved  in  an  acid,  and  is  manufactured 
for  use  as  a  manure,  by  decomposing  bone-ash  with  sulphuric  acid.  It 
crystallizes  in  pearly  plates;  very  soluble  in  water,  the  solution  being 
acid. 

Physiological. — All  three  calcium  phosphates,  accompanied  by  the 
corresponding  magnesium  salts,  exist  in  the  animal  economy.  The  tri- 
calcic  salt  occurs  in  all  the  solids  of  the  body  and  in  all  fluids  not  having 
an  acid  reaction,  being  held  in  solution  in  the  latter  by  the  presence  of 
chlorides.  In  the  fluids  it  is  present  in  very  small  quantity,  except  in  the 
milk,  in  which  it  is  comparatively  abundant;  2.5  to  3.95  parts  per  1,000  in 
human  milk,  and  1.8  to  3.87  parts  per  1,000  in  cow's  milk;  constituting 
about  70  per  cent,  of  the  ash.  The  bones  contain  about  35  parts  of 
organic  matter,  combined  with  G5  parts  of  mineral  material.  The  average 


CALCIUM. 


413 


composition  of  human  bone-ash  is  tricalcic  phosphate,  83.89;  calcium  car- 
bonate, 13.03;  calcium  combined  with  chlorine,  iluorine,  and  organic 
acids,  0.35;  fluorine,  0.23;  chlorine,  0.18.  The  average  quantity  of  tri- 
calcic phosphate  in  male  adult  bones  is  57  per  cent.;  that  of  calcium  car- 
bonate, 10  per  cent.;  and  that  of  trimagnesic  phosphate,  1.3  per  cent.  In 
pathological  conditions  the  composition  of  bone  is  modified  as  shown  in 
the  following  table: 

ANALYSES  OP  BONES. 


ft 

11 

|| 

of  m 
jf 

4 

3 

f) 

1 

fl 

In  100  parts. 

>,^ 

B  *  n' 

.2 

.2    • 

Tl 

«9 

.2* 

*1* 

III 

ll  i 

|§  ei 

2  *3 

'•§  1 

1 

li's 

2 

w  =  a 

3«£ 

«s 

I2 

5 

|8P« 

1 

48.  as 

32.54 

75.22 

72.20 

,             j 

25.69 

41.42 

19.58 

Fats                                  

29.18 

4.15 

6.12 

7.20 

-<  81  .12  r 

3  00 

8.36 

1.23 

Tricalcic  phosphate    

56.9 

17.56 

53.25 

12.56 

14.78 

15.60 

1.00 

[•51.53 

44.05 

72.63 

Calcium  carbonate  

10.9 

3.04 

7.49 

3.20 

3.00 

2  66 

544 

3.45 

4.03 

Trimagnesic  phosphate  

1.3 

0.23 

1.22 

0.92 

0.80 

3.43 

1.02 

1.93 

Other  salts  

0.37 

1.35 

1.98 

1.02 

0  62 

0  91 

1.70 

0.61 

35.8 

78.01 

36.69 

81.34 

79.40 

81.12 

38  69 

49.78 

20.80 

64.2 

21  20 

63.31 

19.66 

20  60 

18  88 

61  31 

50.22 

79.20 

*  Included  in  tricalcic  phos- 

. 

d 

I 

1 

1 

A 

Id 

1*6' 

J 

phate. 

41 

c 

w 

f 

B 

fS  5 

a 

I 

3 

| 

3 

i 

i 

«     rt 

* 

o 

The  teeth  consist  largely  of  tricalcic  phosphate.  Von  Bibra  gives  for 
the  enamel  of  the  molars  in  man,  89.83  per  cent,  of  this  salt,  and  for  the 
dentine,  66.72  per  cent. 

From  the  urine,  tricalcic  phosphate  is  frequently  deposited,  either  in 
the  form  of  an  amorphous,  granular  sediment,  or  as  calculi.  The  dicalcio 
salt  occurs  occasionally  in  urinary  sediments,  in  the  form  of  needle- 
shaped  crystals  arranged  in  rosettes,  and  also  in  urinary  calculi.  The 
monocalcic  salt  is  always  present  in  acid  urine,  constituting,  with  the 
corresponding  magnesium  salt,  the  earthy  phosphates.  The  total  elimina- 
tion of  phosphoric  acid  by  the  urine  is  about  2.76  grams  in  twenty-four 
hours,  of  which  two-thirds  is  in  combination  with  alkaline  metals,  and  one- 
third  in  the  phosphates  of  calcium  and  magnesium.  The  hourly  elimina- 
tion follows  about  the  same  variation  as  that  of  the  chlorides.  The  total 
elimination  is  greater  with  animal  than  with  vegetable  food;  is  diminished 
during  pregnancy;  and  is  above  the  normal  during  excessive  mental  work. 
The  elimination  of  earthy  phosphates  is  greatly  increased  in  osteomala- 
cia,  often  so  far  that  they  are  in  excess  of  the  alkaline  phosphates. 

So  long  as  the  urine  is  acid,  it  contains  the  soluble  acid  phosphates; 
when  the  reaction  becomes  alkaline,  or  even  on  loss  of  carbon  dioxide  by 
exposure  to  air,  the  acid  phosphate  is  converted  into  the  insoluble  trical- 
cic phosphate.  Alkaline  urines  are  for  this  reason  almost  always  turbid, 
and  become  clear  on  the  addition  of  acid.  It  is  in  such  urine  that  phos- 
phatic  calculi  are  invariably  formed,  usually  about  a  nucleus  of  uric  acid 
or  of  a  foreign  body.  If  the  alkalinity  be  due  to  the  formation  of  ammo- 
nia, the  trimagnesio  phosphate  is  not  formed,  but  ammonio-magnesium 
phosphate  (q.  v.). 

A  process  for  determining  the  quantity  of  phosphates  in  urine  is 


414  GENERAL    MEDICAL    CHEMISTRY. 

based  upon  the  formation  of  the  insoluble  uranium  phosphate,  and  upon 
the  production  of  a  brown  color  when  a  solution  of  a  uranium  salt  is 
brought  in  contact  with  a  solution  of  potassium  ferrocyanide.  Four  so- 
lutions are  required:  1st,  a  standard  solution  of  disodic  phosphate; 
made  by  dissolving  10.085  grams  of  crystallized,  non-effloresced  disodic 
phosphate  in  water,  and  diluting  to  a  litre;  2d,  an  acid  solution  of 
sodium  acetate,  made  by  dissolving  100  grains  sodium  acetate  in  water, 
adding  100  c.c.  glacial  ace  tic  •>  acid,  anil  diluting  with  water  to  a  litre; 
3d,  a  strong  solution  of  potassium  ferrocyanide;  4th,  a  standard  so- 
lution of  uranium  acetate,  made  by  dissolving  20.3  grams  of  yellow  ura- 
nic  oxide  in  glacial  acetic  acid,  and  diluting  with  water  to  nearly  a  litre. 
Solution  1  serves  to  determine  the  true  strength  of  this  solution, 
as  follows:  50  c.c.  of  Solution  1  are  placed  in  a  beaker,  5  c.c.  of  Solu- 
tion 2  are  added,  the  mixture  heated  on  a  water-bath,  and  the  uranium 
solution  gradually  added  from  a  burette  until  a  drop  from  the  beaker 
produces  a  brown  color  when  brought  in  contact  with  a  drop  of  the  fer- 
rocyanide solution.  At  this  point  the  reading  of  the  burette,  which  indi- 
cates the  number  of  c.c.  of  the  uranium  solution,  corresponding  to 
0.1 — P,,O6,  is  taken.  A  quantity  of  water,  determined  by  calculation 
from  the  result  thus  obtained,  is  then  added  to  the  remaining  uranium 
solution,  such  as  to  render  each  cubic  centimetre  equivalent  to  0.005 
gram  phosphoric  anhydride. 

To  determine  the  total  phosphates  in  a  urine:  50  c.c.  are  placed  in 
a  beaker,  5  c.c.  sodium  acetate  solution  are  added;  the  mixture  is 
heated  on  the  water-bath,  and  the  uranium  solution  delivered  from  a 
burette  until  a  drop,  removed  from  the  beaker  and  brought  in  contact 
with  a  drop  of  ferrocyanide  solution,  produces  a  brown  tinge.  The  bu- 
rette reading,  multiplied  by  0.005,  gives  the  amount  of  phosphoric  anhy- 
dride in  50  c.c.  urine;  and  this,  multiplied  by  -fa  the  amount  of  urine 
passed  in  24  hours,  gives  the  daily  elimination. 

To  determine  the  earthy  phosphates,  a  sample  of  100  c.c.  urine  is  ren- 
dered alkaline  with  ammonia  and  set  aside  for  12  hours;  the  precipitate 
is  then  collected  upon  a  filter,  washed  with  ammoniacal  water,  brought 
into  a  beaker,  dissolved  in  a  small  quantity  of  acetic  acid;  the  solution 
diluted  to  50  c.c.  with  water,  treated  with  5  c.c.  sodium  acetate  solution, 
and  the  amount  of  phosphoric  anhydride  determined  as  above. 

CARBONATES.  —  Calcium  carbonate  —  Golds  carbonas  pra?cipitata 
(U.  S.,  Br.) — C03Ca — the  most  abundant  of  the  natural  compounds  of 
calcium,  exists  as  limestone,  calk  spar,  chalk,  marble,  Iceland  spar,  and 
arragonite,  and  forms  the  mineral  basis  of  the  corals,  shells  of  Crustacea, 
and  of  molluscs,  etc. 

The  precipitated  chalk,  Calcii  carbonas  proscipitata  (U.  S.,  Br.),  is  pre- 
pared by  precipitating  a  solution  of  calcium  chloride  with  one  of  sodium 
carbonate.  Prepared  chalk,  Creta  prceparata  (U.  S.,  Br.),  is  native 
chalk,  purified  by  grinding  with  water,  diluting,  allowing  the  coarser 
particles  to  subside,  decanting  the  still  turbid  liquid,  collecting,  and  dry- 
ing the  finer  particles;  a  process  known  as  elutriation. 

It  is  a  white  powder,  almost  insoluble  in  pure  water;  much  more  sol- 
uble in  water  containing  carbonic  acid,  the  solution  being  regarded  as 
containing  hydrocalcic  carbonate  (C03)2H2Ca.  At  a  red  heat  it  yields 
carbon  dioxide  and  calcic  oxide.  It  is  decomposed  by  acids  with  liber- 
ation of  carbon  dioxide. 

Physiological. — Calcium  carbonate  is  much  more  abundant  in  the 
lower  than  in  the  higher  forms  of  animal  life.  It  occurs  in  the  egg-shells 


BARIUM.  415 

of  birds,  in  the  bones  and  teeth  of  all  animals;  in  solution  in  the  saliva 
and  urine  of  the  herbivora,  and  deposited  in  the  crystalline  form,  as  oto- 
llths,  in  the  internal  ear  of  man.  It  is  deposited  pathologically  in  calcifi- 
cations, in  parotid  calculi,  and  occasionally  in  human  urinary  calculi  and 
sediments. 

OXALATE — Oxalate  of  lime — C2O4Ca — exists  in  the  sap  of  many 
plants,  and  is  formed  as  a  white,  crystalline  precipitate  by  double  decom- 
position between  a  calcium  salt  and  an  alkaline  oxalate.  It  is  insoluble 
in  water,  acetic  acid,  or  ammonium  hydrate;  soluble  in  the  mineral  acids 
and  in  solution  of  acid  sodium  phosphate. 

Physiological. — Calcium  oxalate  is  taken  into  the  body  in  vegetable 
food,  and  is  formed  in  the  economy,  where  its  production  is  intimately 
connected  with  that  of  uric  acid. 

It  occurs  in  the  urine,  in  which  it  is  increased  in  quantity  when  large 
amounts  of  vegetable  food  are  taken,  when  sparkling  wines  or  beers  are 
indulged  in;  and  when  the  carbonates  of  the  alkalies,  lime-water,  and 
lemon-juice,  are  administered.  It  is  deposited  as  a  urinary  sediment  in 
the  form  of  small,  brilliant  octohedra,  having  the  appearance  of  the 
backs  of  square  letter-envelopes,  or  in  dumb-bells.  It  is  usually  deposited 
from  acid  urine,  and  accompanied  by  crystals  of  uric  acid.  Sometimes, 
however,  it  occurs  in  urines  undergoing  alkaline  fermentation,  in  which 
case  it  is  accompanied  by  crystals  of  ammonio-magnesian  phosphate. 

The  renal  or  vesical  calculi  of  calcium  oxalate,  known  as  mulberry  cal- 
culi, are  dark  brown  or  gray,  very  hard,  occasionally  smooth,  generally 
tuberculated,  soluble  in  hydrochloric  acid  without  effervescence;  and 
when  ignited,  they  blacken,  turn  white,  and  leave  an  alkaline  residue. 

Analytical  characters. — Ammonium  sulphydrate  nothing,  unless 
the  calcium  salt  be  the  phosphate,  oxalate,  or  fluoride  in  acid  solution, 
when  it  forms  a  white  precipitate.  Alkaline  carbonates,  white  precipi- 
tate, not  prevented  by  the  presence  of  ammoniacal  salts.  Ammonium 
oxalate,  white  precipitate,  insoluble  in  acetic  acid;  soluble  in  hydro- 
chloric or  nitric  acid.  Sulphuric  acid,  white  precipitate,  from  solutions 
which  are  not  too  dilute;  very  sparingly  soluble  in  water,  insoluble  in  al- 
cohol; soluble  in  sodium  hyposulphite  solution.  Sodium  tungstate, 
dense  white  precipitate,  even  from  dilute  solutions.  Colors  the  flame  of 
the  Bunsen  burner  reddish  yellow. 


BARIUM. 
Ba 137.2 

The  element  itself  is  not  of  interest. 

Oxides. — BARIUM  MONOXIDE — Baryta — BaO — is  prepared,  by  calcin- 
ing the  nitrate,  as  a  grayish  white  caustic  earth.  It  unites  readily  with 
water  to  form  a  hydrate,  BaH202,  whose  aqueous  solution  is  baryta  water. 

Chloride — Barii  chloridum  (U.  S.)— BaCl2  +  2  Aq. — is  obtained  by 
treating  the  native  sulphide,  or  carbonate,  with  hydrochloric  acid.  It 
forms  crystalline  plates,  permanent  in  air,  soluble  in  water. 

Analytical  characters. — Alkaline  carbonates,  white  precipitate  in 
alkaline  solution.  Sulphuric  acid,  or  calcium  sulphate,  white  precipi- 
tate, insoluble  in  acids.  Sodium  phosphate,  white  precipitate,  soluble  in 
nitric  acid.  Colors  the  Bunsen  flame  greenish  yellow. 

Action  on  the  economy. — The  oxides  and  hydrate  act  as  corro- 


416  GENERAL    MEDICAL    CHEMISTRY. 

sives  by  virtue  of  their  alkalinity,  and  also  as  true  poisons.  All  soluble 
compounds  of  barium,  and  those  which  are  readily  converted  into  soluble 
compounds  in  the  stomach,  are  actively  poisonous.  Soluble  sulphates, 
followed  by  emetics,  are  indicated  as  antidotes. 


IV.     MAGNESIUM  GROUP. 
MAGNESIUM,  Mg,  24;  ZINC,  Zn,  65.2;  CADMIUM,  Cd,  112. 

Each  of  these  elements  forms  a  single  oxide — a  corresponding  basic 
hydrate,  and  a  series  of  salts  in  which  its  atoms  are  divalent. 

MAGNESIUM. 
Mg 24 

Is  prepared  by  heating  its  chloride  with  sodium.  It  is  a  white  metal; 
sp.  gr.  1.75;  fuses  at  1000°;  burns  with  great  brilliancy  in  air;  decom- 
poses vapor  of  water  when  heated;  reduces  carbon  dioxide  with  the  aid 
of  heat;  combines  directly  with  chlorine,  sulphur,  phosphorus,  arsenic, 
and  nitrogen;  dissolves  in  dilute  acids,  but  is  not  affected  by  alkaline 
solutions. 

Oxide — Calcined  magnesia — Magnesia  (U.  S.,  Br.) — MgO — is  ob- 
tained by  calcining  the  carbonate,  hydrate,  or  nitrate.  Is  a  light,  bulky, 
white  powder,  odorless,  and  tasteless;  has  an  alkaline  reaction;  almost  in- 
soluble in  water;  dissolves  readily  in  dilute  acids  without  effervescence. 

Hydrate — Hydrated  magnesia — MgH2O2 — is  formed  when  a  solution 
of  a  magnesium  salt  is  precipitated  with  sodium  hydrate  in  excess,  in  the 
absence  of  ammoniacal  salts.  It  exists  in  mixtures  holding  it  in  suspen- 
sion in  water  (milk  of  magnesia) ,  used  as  antidotes  to  the  effects  of  acid 
corrosives. 

Chloride,  MgClu — is  obtained  by  dissolving  the  carbonate  in  hydro- 
chloric acid.  It  is  one  of  the  most  deliquescent  substances  known,  and 
imperfectly  purified  table-salt  containing  it,  along  with  calcium  chloride, 
becomes  damp  on  exposure  to  air. 

Salts. — SULPHATE — Epsom  salt — Sedlitz  salt — Magnesii  sulphas  (U. 
S.) — Magnesias  sulphas  (Br.) — SO4Mg-f7Aq. — exists  in  solution  in  sea- 
water  and  in  the  waters  of  many  mineral  springs,  especially  in  those  belong- 
ing to  the  class  of  bitter  waters.  It  is  obtained  artificially  by  the  action  of 
sulphuric  acid  upon  magnesium  carbonate.  It  crystallizes  in  rhombic 
needles;  fuses  and  gradually  loses  water  of  crystallization  up  to  132°, 
when  it  retains  1  Aq.,  which  is  driven  off  at  210°.  It  dissolves  in  0.8 
parts  of  water  at  19°. 

PHOSPHATES. — These  phosphates  resemble  those  of  calcium  in  their 
constitution  and  properties,  and  accompany  them  in  the  situations  in 
which  they  occur  in  the  animal  body,  but  in  much  smaller  quantity. 

Magnesium  also  forms  double  phosphates,  constituted  by  the  substitu- 
tion of  one  atom  of  the  divalent  metal  for  two  of  the  atoms  of  basic  hy- 
drogen, of  a  molecule  of  phosphoric  acid  and  of  an  atom  of  an  alkaline 
metal,  or  of  an  ammonium  group,  for  the  remaining  basic  hydrogen. 


MAGNESIUM.  417 

One  of  these  compounds  is  ammonio-magnesian  phosphate  /  triple  phos- 
phate, PO4Mg(NH4)  +  GAq. — which  is  formed  when  excess  of  an  alkaline 
phosphate  and  of  ammonia  are  added  to  a  solution  containing  magnesium. 

In  the  urine,  alkaline  phosphates  and  magnesium  salts  are  always 
present,  and  consequently  when,  by  decomposition  of  urea,  the  urine  be- 
comes alkaline,  the  conditions  for  the  formation  of  this  compound  are 
fulfilled;  and  being  practically  insoluble,  especially  in  the  presence  of 
excess  of  phosphates  and  of  ammonia,  it  is  deposited  in  crystals,  usually 
tabular,  sometimes  feathery  and  stellate  in  form.  When  it  is  formed  in 
the  bladder,  in  the  presence  of  some  body  to  serve  as  a  nucleus,  the 
crystallization  takes  place  upon  the  nucleus  and  a  fusible  calculus  is 
produced. 

SILICATES  constitute  a  number  of  important  minerals:  talc,  steatite  or 
soapstone,  asbestos,  and  meerschaum. 

CARBONATES. — Magnesium  carbonate — Neutral  carbonate — CO3Mg — 
exists  in  magnesite,  and,  combined  with  calcium  carbonate,  in  dolomite. 
It  cannot  be  formed,  like  most  other  carbonates,  by  decomposing  a 
magnesium  salt  with  an  alkaline  carbonate,  but  may  be  produced  by 
passing  carbon  dioxide  through  water  holding  tetramagnesic  tricarbonate 
in  suspension.  Trimagnesic  dicarbonate,  2(C03Mg),MgH2O2+2H2O — is 
formed  in  small  crystals  when  a  solution  of  magnesium  sulphate  is  pre- 
cipitated with  excess  of  sodium  carbonate  and  the  mixture  boiled.  Tetra- 
magnesic tricarbonate — Magnesia  alba — Magnesii  carbonas  (U.  S.) — 
Magnesias  carbonas  (Br.) — 3(CO3Mg),MgH2O2  +  3H20 — occurs  in  com- 
merce in  the  form  of  light,  white  cubes,  composed  of  a  powder  which  is 
amorphous  or  partly  crystalline.  It  is  prepared  by  precipitating  a  solu- 
tion of  magnesium  sulphate  with  one  of  sodium  carbonate;  if  the  pre- 
cipitation occur  in  cold  dilute  solutions  (Magnesice  carbonas  laevis,  Br.), 
very  little  carbon  dioxide  is  given  off ;  alight,  bulky  precipitate  falls,  and 
the  solution  contains  magnesium,  probably  in  the  form  of  the  bicarbonate 
(CO3)2H2Mg. ;  this  solution,  on  standing,  deposits  crystals  of  the  carbo- 
nate, CO3Mg  +  3Aq.  If  hot  concentrated  solutions  be  used  and  the  liquid 
then  boiled  upon  the  precipitate,  carbon  dioxide  is  given  off,  and  a  denser, 
heavier  precipitate  is  formed,  which  varies  in  composition  according  to 
the  length  of  time  during  which  the  boiling  is  continued,  and  to  the  pres- 
ence or  absence  of  excess  of  sodium  carbonate.  The  pharmaceutical  pro- 
duct is  intended  to  have  the  composition  given  above;  it  frequently  con- 
tains 4(C03Mg),MgH203  +  4H20,  or  even  2(C03Mg),MgII202+2HaO. 
All  of  these  compounds  are  very  sparingly  soluble  in  water,  but  much 
more  soluble  in  water  containing  ammoniacal  salts. 

Analytical  characters. — Ammonium  hydrate,  voluminous  white 
precipitate  from  neutral  solutions.  Potassium  or  sodium  hydrate,  volu- 
minous white  precipitate  from  warm  solutions;  prevented  by  the  pres- 
ence of  ammonium  salts  and  of  certain  organic  substances.  Ammonium 
carbonate,  slight  precipitate  from  hot  solutions;  prevented  by  the  pres- 
ence of  ammoniacal  salts.  Sodium  or  potassium  carbonate,  white  pre- 
cipitate, best  from  hot  solution;  prevented  by  the  presence  of  ammoni- 
acal compounds.  Disodic  phosphate,  white  precipitate  in  hot,  not  too 
dilute  solutions.  Oxalic  acid,  nothing  alone,  but  in  the  presence  of  am- 
monium hydrate  a  white  precipitate;  not  formed  in  the  presence  of  the 
salts  or  chloride  of  ammonium. 
27 


418  GENERAL    MEDICAL    CHEMISTRY. 

ZINC. 
Zn 65.2 

Is  a  bluish  white  metal  ;  either  crystalline,  granular,  or  fibrous. 
Pure  zinc  is  quite  malleable- and  ductije;  the  commercial  is  usually  brit- 
tle; at  130°— 150°  it  is  pliable;  at  200°— 210°  it  again  becomes  brittle; 
it  fuses  at  415°,  and  distils  at  1040°;  sp.  gr.  6.862  if  cast,  7.215  if  rolled; 
at  500°  it  burns  with  a  greenish  flame  and  gives  off  snowy  flakes  of  the 
oxide  (lana  philosophica,  pompholix).  In  moist  air  it  becomes  coated 
with  a  hydrocarbonate.  Pure  sulphuric  acid,  SO4H2,  is  not  affected  by 
pure  zinc  in  the  cold;  the  commercial  metal  dissolves  in  the  diluted  acid 
with  evolution  of  hydrogen;  the  action  is  more  rapid  in  the  presence  of 
copper  or  platinum,  less  so  in  that  of  mercury.  It  also  decomposes  nitric, 
hydrochloric,  and  acetic  acids. 

When  required  in  toxicological  analysis,  it  must  be  free  from  arsenic, 
and,  in  some  instances,  from  phosphorus.  It  is  better  to  test  samples 
until  a  pure  one  is  found,  than  to  attempt  the  purification  of  a  contami- 
nated metal. 

Oxide — Zinci  oxidum  (U.  S.,  Br.) — ZnO — is  prepared  either  by  cal- 
cining the  precipitated  carbonate,  or  by  burning  the  metal  in  a  current 
of  air.  An  impure-  oxide,  known  as  tutty,  is  deposited  in  the  flues  of 
zinc  furnaces  and  in  those  in  which  brass  is  fused.  When  obtained  by 
calcination  of  the  carbonate,  it  forms  a  soft,  white,  tasteless,  and  odorless 
powder;  when  produced  by  burning  the  metal,  it  occurs  in  light,  volumi- 
nous, white  masses.  It  is  neither  fusible,  volatile,  nor  decomposable  by 
heat,  and  is  completely  insoluble  in  neutral  solvents.  It  dissolves  in  dilute 
acids,  with  formation  of  the  corresponding  salts. 

It  is  used  in  the  arts  as  a  white  pigment  in  place  of  lead  carbonate, 
and  is  not  darkened  by  hydrogen  sulphide. 

Zinc  hydrate,  ZnH9O., — cannot  be  obtained  by  union  of  the  oxide 
with  water,  but  is  formed  when  a  solution  of  a  zinc  salt  is  precipitated 
by  potash.  It  is,  when  freshly  precipitated,  very  soluble  in  alkalies  and 
in  solutions  of  ammoniacal  salts. 

Chloride — Butter  of  zinc — Zinci  chloridum  (U.  S.,  Br.) — ZnCl3-f  Aq. 
— is  obtained  by  dissolving  zinc  in  hydrochloric  acid.  It  forms  a  soft, 
white  mass;  very  deliquescent,  fusible,  and  volatile;  extremely  soluble  in 
water,  freely  soluble  in  alcohol;  its  solution  has  a  burning,  metallic 
taste,  destroys  vegetable  tissues,  dissolves  silk,  and  exerts  a  strong,  dehy- 
drating action  upon  organic  substances  in  general. 

In  dilute  solution  it  is  used  as  a  disinfectant  (Burnett's  fluid),  as  a 
preservative  of  wood,  and  as  an  embalming  injection. 

Salts. — SULPHATE —  White  vitriol — Zinci  sulphas  (U.  S.,  Br.) — SO4 
Zn-}-wH2O — is  formed  when  zinc,  or  its  oxide,  sulphide,  or  carbonate  is 
dissolved  in  dilute  sulphuric  acid.  It  crystallizes  below  30°,  with  7Aq.; 
at  30°,  with  6  Aq.;  between  40°  and  50°,  with  5  Aq.;  at  0°  from  a  con- 
centrated, acid  solution,  with  4Aq. ;  with  2Aq.,  as  a  crystalline  powder 
deposited  from  a  boiling  solution  by  the  addition  of  concentrated  sul- 
phuric acid;  with  1  Aq.  from  a  saturated  solution  at  100°;  finally,  anhy- 
drous, by  heating  the  preceding  to  238°. 

The  salt  usually  met  with  is  that  with  7  Aq.,  which  is  very  soluble  in 
water;  insoluble  in  absolute  alcohol,  sparingly  soluble  in  weak  alcohol. 


ZINC.  419 

Its  solutions  have  a  strong,  styptic  taste;  coagulate  albumin  when  added 
in  moderate  quantity,  the  coagulum  dissolving  in  an  excess,  and  form 
insoluble  precipitates  with  the  tannins. 

Analytical  characters. — Hydrate,  of  potassium,  sodium,  or  ammo- 
nium— white  precipitate,  soluble  in  excess.  Potassium,  or  sodium  car- 
bonate, white  precipitate  in  the  absence  of  ammoniacal  salts.  Hydrogen 
sulphide,  in  neutral  solution,  white  precipitate;  in  presence  of  an  excess 
of  a  mineral  acid,  this  precipitation  is  prevented  unless  sodium  acetate  is 
also  present.  Ammonium  sulphydrate,  white  precipitate,  insoluble  in 
excess,  in  potassium  or  ammonium  hydrate,  or  in  acetic  acid;  soluble  in 
dilute  mineral  acids.  Ammonium  carbonate,  white  precipitate,  soluble 
in  excess.  Diso die  phosphate,  in  the  absence  of  ammoniacal  salts,  white 
precipitate,  soluble  in  acids  or  alkalies.  Potassium  ferrocyanide,  white 
precipitate,  insoluble  in  hydrochloric  acid. 

Action  on  the  economy. — All  the  compounds  of  zinc  which  are 
soluble  in  the  digestive  fluids  behave  as  true  poisons;  and  solutions  of  the 
chloride  (in  common  use  by  tinsmiths,  and  in  disinfecting  fluids)  have  also 
well-marked  corrosive  properties.  When  zinc  compounds  are  taken,  it 
is  almost  invariably  by  mistake  for  other  substances:  the  sulphate  for 
Epsom  salt,  and  solutions  of  the  chloride  for  various  liquids,  gin,  fluid 
magnesia,  vinegar,  etc. 

Metallic  zinc  is  dissolved  by  solutions  containing  sodium  chloride,  or 
organic  acids,  for  which  reason  articles  of  food  kept  in  vessels  of  galvan- 
ized iron  become  contaminated  with  zinc  compounds,  and,  if  eaten,  pro- 
duce, more  or  less  intense  symptoms  of  intoxication.  For  the  same  rea^ 
son  materials  intended  for  analysis,  in  cases  of  supposed  poisoning,  should 
never  be  packed  in  jars  closed  by  zinc  caps. 


V.     NICKEL   GROUP. 
NICKEL,  Ni,  59;  COBALT,  Co,  59. 

These  two  elements  bear  a  certain  resemblance  to  those  of  the  iron 
group;  from  which  they  differ  in  forming,  so  far  as  known,  no  compounds 
similar  to  the  ferrates,  chromates,  and  manganates.  They  form  com- 
pounds corresponding  to  the  sesquioxide  of  iron,  but  the  salts  correspond- 
ing to  the  ferric  series  are  wanting,  or  exceedingly  unstable  if  they  exist. 

Analytical  characters. — NICKEL — Ammonium  sulphydrate,  black 
precipitate,  insoluble  in  excess.  Potassium,  or  sodium  hydrate,  apple- 
green  precipitate  in  the  absence  of  tartaric  acid;  insoluble  in  excess. 
Ammonium  hydrate,  apple-green  precipitate,  soluble  in  excess;  this  solu- 
tion is  violet  and  deposits  the  hydrate  when  heated  with  potash. 

COBALT. — Ammonium  sulphydrate,  brown-black  precipitate,  insoluble 
in  excess.  Potash,  blue  precipitate,  turns  red  slowly  in  the  cold;  quickly 
if  heated;  not  formed  in  the  cold  in  the  presence  of  ammoniacal  salts. 
Ammonium  hydrate,  blue  precipitate;  turns  red  in  the  absence  of  air, 
green  in  its  presence. 


420  GENERAL    MEDICAL    CHEMISTRY. 

VI.  COPPER   GROUP. 
COPPER,  Cu,  63.5;  MERCURY,  Hg,  200. 

Each  of  these  elements  forms  two  series  of  compounds;  one  of  which 

/Cu     \ 
contains  the  divalent  group!-'  ,    /I"  oj  (Hg2)"  and  is  designated  by  the 

\Cu'  / 

termination   ous  j  the  other  contains  the  single,  divalent  atoms,  and  is 
designated  by  the  termination  ic. 

COPPER. 
Cuprum Cu 63.5 

A  yellowish  red  metal,  dark  brown  when  finely  divided;  sp.  gr.  8.914 
r— 8.952;  very  malleable,  ductile,  and  tenacious;  a  good  conductor  of 
heat  and  of  electricity.  It  is  unaltered  in  dry  air;  in  damp  air  it  is  coated 
with  a  green  basic  carbonate;  heated  to  redness  in  air,  it  is  oxidized.  Hot 
sulphuric  acid  dissolves  it  with  liberation  of  sulphur  dioxide;  nitric  acid, 
with  liberation  of  nitrogen  dioxide;  and  hot  hydrochloric  acid,  with  libera- 
tion of  hydrogen.  Weak  acids  form  soluble  salts  with  it  in  presence  of 
air  and  moisture.  Ammonium  hydrate  is  colored  blue  by  contact  of  air 
and  copper. 

Oxides. — CUPROUS  OXIDE  —  Suboxide  or  black  oxide — (Cu2)O — is 
formed  as  a  red  or  yellow  powder,  by  calcining  a  mixture  of  cuprous  chlo- 
ride and  sodium  carbonate. 

A  yellow  hydrate  is  precipitated  when  cupric  salts  are  decomposed  by 
boiling  with  glucose  (Fehling's  and  Trommer's  tests).  It  loses  its  water 
of  hydration  at  360°. 

CUPRIC  OXIDE — Binoxide — Black  oxide — CuO — is  prepared  by  heat- 
ing copper  to  dull  redness  in  a  current  of  air,  or  by  calcining  its  nitrate. 
It  is  also  formed  by  the  precipitation  of  a  boiling  solution  of  a  cupric 
salt  by  potash,  and  prolonged  boiling  of  the  liquid  on  the  precipitate. 

It  is  black,  or  dark  reddish  brown,  amorphous,  and  is  reduced  by  char- 
coal, hydrogen,  sodium,  or  potassium,  at  comparatively  low  temperatures. 
When  heated  in  the  presence  of  organic  substances,  it  gives  up  its  oxy- 
gen, converting  the  carbon  of  the  organic  body  into  carbon  dioxide,  and 
its  hydrogen  into  water.  It  dissolves  in  acids  with  formation  of  salts. 

Sulphides. — CUPROUS  SULPHIDE — Subsidphide  or  Protosidphide — 
Cu2S — occurs  in  nature  in  soft,  fusible,  gray  crystals  (chalcosirte  or  copper 
glance),  and  in  many  double  sulphides,  among  which  is  a  double  sulphide 
of  copper  and  iron,  known  as  copper  pyrites. 

CUPRIC  SULPHIDE — Protosulphide — CuS — is  obtained  by  treating  a 
solution  of  a  cupric  salt  with  hydrogen  sulphide  or  ammonium  sulphydrate. 
It  is  almost  black  when  moist,  greenish  brown  when  dry.  Hot  nitric 
acid  oxidizes  it  to  cupric  sulphate;  hot  hydrochloric  acid  converts  it  into 
cupric  chloride,  with  separation  of  sulphur  and  formation  of  hydrogen  sul- 
phide. It  is  sparingly  soluble  in  ammonium  sulphydrate,  its  solubility 
being  increased  by  the  presence  of  organic  matter. 

Chlorides. — CUPROUS  CHLORIDE — Subchloride  or  Protochloride — Cu, 
Cla — is  prepared  by  heating  copper  with  one  of  the  chlorides  of  mercury ; 


COPPER.  421 

by  dissolving  cuprous  oxide  in  hydrochloric  acid  without'  contact  of  air; 
or  by  the  action  of  reducing  agents  upon  solutions  of  cupric  chloride.  It 
is  a  heavy,  white  powder;  turns  violet  and  blue  by  exposure  to  lightj 
soluble  in  concentrated  hydrochloric  acid',  insoluble  in  water.  It  forms  a 
crystallizable  compound  with  carbon  monoxide,  and  its  solution  in  hydro- 
chloric acid  is  used  in  analysis  to  absorb  that  gas. 

CUPRIC  CHLORIDE — Chloride  or  Deutochloride — CuCl2 — is  formed  by 
dissolving  copper  in  aqua  regia;  if  copper  be  present  in  excess,  it  reduces 
the  cupric  to  cuprous  chloride.  It  crystallizes  in  bluish  green,  rhombic 
prisms  with  2  Aq.,  deliquescent,  very  soluble  in  water  and  in  alcohol. 

Salts. — NITRATES.— Cuprous  nitrate  is  unknown.  Cupric  nitrate, 
(NO3)2Cu — is  formed  by  dissolving  copper,  or  its  oxide,  or  carbonate  in 
nitric  acid.  It  crystallizes  at  20°  to  25°  with  3  Aq.  ;  below  20°  with 
6  Aq. 

SULPHATES. — The  existence  of  cuprous  sulphate  is  doubtful.  Cuprie 
sulphate — Sulphate  of  copper — J3lue  vitriol — Bluestone —  Cupri  sulphas 
(U.  S.,  Br.) — SO4Cu-{-5Aq. — is  prepared:  1st,  by  roasting  copper  py- 
rites; 2d,  from  the  water  of  copper-mines;  3d,  by  exposing  copper,  moist- 
ened with  dilute  sulphuric  acid,  to  air;  4th,  by  heating  copper  with  con- 
centrated sulphuric  acid. 

As  ordinarily  crystallized,  it  is  in  fine,  blue,  oblique  prisms,  which 
require  for  their  solution  2.71  parts  of  water  at  19°;  and  0.55  parts  at 
100°.  Insoluble  in  alcohol.  The  crystals  effloresce  in  dry  air  at  15°,  losing 
2  Aq.;  at  100°  they  still  retain  1  Aq.,  which  they  lose  at  230°,  forming 
a  white,  amorphous  powder.  The  anhydrous  salt,  in  taking  up  water,  re- 
sumes its  blfte  color.  Its  solutions  are  blue,  acid,  styptic,  and  metallic  in 
taste. 

When  ammonium  hydrate  is  added  to  a  solution  of  cupric  sulphate, 
a  bluish  white  precipitate  falls,  which  redissolves  in  excess  of  the  alkali, 
to  form  a  deep  blue  solution ;  strong  alcohol  floated  over  the  surface  of 
this  solution  separates  long,  right  rhombic  prisms,  having  the  composi- 
tion SO4Cu,4NH3  +  HQO,  which  are  very  soluble  in  water;  their  solution 
constitutes  ammonio-sidphate  of  copper  or  aqua  sapphirina;  and  they 
exist,  mixed  with  other  substances,  in  the  cuprum  ammoniatum  (U.  S.). 

ARSENITE — Scheele's  green — Mineral  green — is  a  mixture  of  cuprie 
arsenite  and  hydrate;  prepared  by  adding  potassium  arsenite  to  solution 
of  cupric  sulphate.  It  is  a  grass-green  powder,  insoluble  in  water;  solu- 
ble in  ammonium  hydrate,  or  in  acids.  Exceedingly  poisonous. 

Schweinfurt  green — Mitis  green  or  Paris  green — is  the  most  fre- 
quently used,  and  the  most  dangerous  of  the  cupro-arsenical  pigments. 
It  is  prepared  by  adding  a  thin  paste  of  neutral  cupric  acetate  with  water 
to  a  boiling  solution  of  arsenious  acid,  and  continuing  the  boiling  during 
a  further  addition  of  acetic  acid.  It  is  an  insoluble,  green,  crystalline 
powder,  having  the  composition  (C2H3O2)2Cu  +  3(As2O4Cu).  It  is  decom- 
posed by  prolonged  boiling  in  water,  by  aqueous  solutions  of  the  alkalies, 
and  by  the  mineral  acids. 

CARBONATES. — The  existence  of  cuprous  carbonate  is  doubtful.  Cu- 
pric carbonate — CO3Cu — exists  in  nature,  but  has  not  been  obtained  arti- 
ficially. Dicupric  carbonate — CO3Cu,CuH2O2 — exists  in  nature  as  mala- 
chite. When  a  solution  of  a  cupric  salt  is  decomposed  by  an  alkaline 
carbonate,  a  bluish  precipitate,  having  the  composition  C03Cu,CuH2Q9 
-f-H.^O,  is  formed,  which,  on  drying,  loses  H2O,  and  becomes  green;  it  is 
used  as  a  pigment  under  the  name  mineral  green.  Tricupric  carbonate — - 
Sesquicarbonate  of  copper — 2(CO3Cu),CuHaOa — exists  in  nature  as  a  blue 


422  GENERAL    MEDICAL    CHEMISTRY. 

mineral  called  azurite  or  mountain  blue,  and  is  prepared  by  a  secret  pro- 
cess for  use  as  a  pigment  known  as  blue  ash. 

ACETATES. —  Cupric  acetate — Diacetate — Crystals  of  Venus — (C2H3 
O,)3Cu  +  Aq. — is  formed  when  cupric  oxide  or  verdigris  is  dissolved  in 
acetic  acid;  or  by  decomposition  of  solution  of  cupric  sulphate  by  lead  ace- 
tate. It  crystallizes  in  large,  bluish  green  prisms,  with  1  Aq.,  which  they 
lose  at  140°;  when  heated  to  240°  or  260°  they  are  decomposed,  with 
liberation  of  glacial  acetic  a'cid.  .; 

Basic  acetates. —  Verdigris — Cupri  subacetas  (U.  S.) — is  a  substance 
prepared  by  exposing  to  air  piles  composed  of  alternate  layers  of  grape- 
skins  and  plates  of  copper,  and  removing  the  bluish  green  coating  from  the 
copper.  It  is  a  mixture,  in  varying  proportions,  of  three  different  sub- 
stances: (C2H302)2Cu,CuH202  +  5Aq.;  [(C2Hs02)2Cu]2,CuH2O2  +  5Aq.; 
and  (C2H302)2Cu,2(CuH202). 

Analytical  characters. — CUPROUS — are  very  unstable  and  readily 
converted  into  cupric  compounds.  Potash,  white  precipitate,  turning 
brownish.  Ammonium  hydrate,  in  absence  of  air,  a  colorless  liquid; 
turns  blue  on  exposure  to  air. 

CUPRIC. — White  when  anhydrous;  when  soluble  in  water  they  form 
blue  or  green  acid  solutions.  Hydrogen  sulphide,  black  precipitate, 
insoluble  in  potassium  or  sodium  sulphide,  sparingly  soluble  in  ammonium 
sulphydrate;  soluble  in  hot  concentrated  nitric  acid  and  in  potassium 
cyanide.  Alkaline  sulphides,  same  as  hydrogen  sulphide.  Potassium  or 
sodium  hydrate,  pale  blue  precipitate,  insoluble  in  excess.  If  the  solution 
be  heated  over  the  precipitate,  the  latter  contracts  and  turns  black.  Am- 
monium hydrate,  in  very  small  quantity,  pale  blue  precipitate;  with  larger 
quantities  a  deep  blue  liquid.  Potassium  or  sodium  carbonate,  greenish 
blue  precipitate,  insoluble  in  excess,  and  turning  black  when  the  liquid  is 
boiled.  Ammonium  carbonate,  pale  blue  precipitate,  soluble  with  deep 
blue  color  in  excess.  Potassium  cyanide,  greenish  yellow  precipitate, 
soluble  in  excess.  Potassium  ferrocyanide,  chestnut-brown  precipitate, 
insoluble  in  weak  acids,  decolorized  by  potash.  Iron  is  coated  with 
metallic  copper. 

Action  on  the  economy.  — The  opinion,  until  recently  universal 
among  toxicologists,  that  all  the  compounds  of  copper  are  poisonous,  has 
been  much  modified  by  recent  researches.  Certain  of  the  copper  com- 
pounds, such  as  the  sulphate,  having  a  tendency  to  combine  with  albu- 
minoid and  other  animal  substances,  produce  symptoms  of  irritation  by 
their  direct  local  action  when  brought  in  contact  with  the  gastric  or  in- 
testinal mucous  membrane.  One  of  the  characteristic  symptoms  of  such 
irritation  is  the  vomiting  of  a  greenish  matter,  which  develops  a  blue 
color  upon  the  addition  of  ammonium  hydrate. 

Cases  are  not  wanting  in  which  severe  illness,  and  even  death,  has 
followed  the  use  of  food  which  has  been  in  contact  with  imperfectly 
tinned  copper  vessels;  cases  in  which  nervous  and  other  symptoms  re- 
ferable to  a  truly  poisonous  action  have  occurred.  As,  however,  it  has 
also  been  shown  that  non-irritant,  pure  copper  compounds  may  be  taken 
in  considerable  doses  with  impunity,  it  appears  at  least  probable  that  the 
poisonous  action  attributed  to  copper  is  due  to  other  substances.  The 
tin  and  solder  used  in  the  manufacture  of  copper  utensils  contain  lead, 
and  in  some  cases  of  so-called  copper-poisoning,  the  symptoms  have  been 
such  as  are  as  consistent  with  lead-poisoning  as  with  copper-poisoning. 
Copper  is  also  notoriously  liable  to  contamination  with  arsenic,  and  it  is 
by  no  means  improbable  that  compounds  of  that  element  are  the  active 


MERCURY.  423 

poisonous  agents  in  some  cases  of  supp'osed  copper-intoxication.  Nor  is 
it  improbable  that  articles  of  food  allowed  to  remain  exposed  to  air  in 
copper  vessels  should  undergo  those  peculiar  changes  which  result  in  the 
formation  of  poisonous  substances,  such  us  the  sausage-  or  cheese-poisons, 
or  the  ptoamines. 

The  treatment,  when  irritant  copper  compounds  have  been  taken, 
should  consist  in  the  administration  of  white  of  egg  or  of  milk,  with 
whose  albuminoids  an  inert  compound  is  formed  by  the  copper  salt.  If 
vomitino-  do  not  occur  spontaneously,  it  should  be  induced  by  the  usual 
methods. 

The  detection  of  copper  in  the  viscera  after  death  is  not  without 
interest,  especially  if  arsenic  have  been  found,  in  which  case  its  discovery 
or  non-discovery  enables  us  to  differentiate  between  poisoning  by  the  ar- 
senical greens  and  that  by  other  arsenical  compounds.  The  detection  of 
mere  traces  of  copper  is  of  no  significance,  because,  although  copper  is 
not  a  physiological  constituent  of  the  body,  it  is  almost  invariably  pres- 
ent, having  been  taken  with  the  food. 

Pickles  and  canned  vegetables  are  sometimes  intentionally  greened  by 
the  addition  of  copper  ;  this  fraud  is  readily  detected  by  inserting  a  large 
needle  into  the  pickle  or  other  vegetable  ;  if  copper  be  present  the  steel 
will  be  found  to  be  coated  with  copper  after  half  an  hour's  contact. 


MERCURY. 

Hydrargyrum Hg 200 

Commercial  mercury  is  contaminated  with  other  metals.  It  may  be 
purified  by  shaking  the  distilled  metal  with  mercurous  nitrate  solution, 
and  preserving  it  under  that  liquid  or  strong  nitric  acid. 

It  is  a  bright,  metallic  liquid;  crystallizes  at  — 40°;  boils  at  360° 
(350°  of  the  air  thermometer);  volatilizes  slightly  at  all  temperatures 
above  —7°;  sp.  gr.  13.596.  It  forms  alloys,  called  amalgams,  with  most 
other  metals;  it  does  not  attack  iron,  and  only  amalgamates  with  platinum 
when  heated.  If  pure,  it  is  not  altered  in  air  at  the  ordinary  tempera- 
ture, but,  if  impure,  is  coated  with  a  gray  film  of  mercuric  oxide;  heated 
in  air  to  near  its  boiling  point,  it  is  oxidized.  It  does  not  decompose 
water.  It  combines  directly  with  chlorine,  bromine,  iodine,  and  sulphur. 
Hot,  concentrated  sulphuric  acid  dissolves  it  with  evolution  of  sulphur 
dioxide,  and  formation  of  mercuric  sulphate.  Nitric  acid  dissolves  it  in 
the  cold  with  formation  of  a  nitrate. 

Hydrargyrum  cum  creta  (U.  S.,  Br.)  and  Uhguentum  hydrargyri 
(U.  S.,  Br.) — owe  their  activity  to  small  quantities  of  mercurous  oxide, 
formed  during  their  preparation;  the  cause  of  the  greater  activity  of  the 
latter  preparation  being  'due  to  a  more  extensive  oxidation.  It  is  also 
probable  that  the  absorption  of  vapor  of  mercury  by  cutaneous  surfaces 
is  preceded  by  its  conversion  into  mercuric  chloride. 

Oxides. — MERCUROUS  OXIDE — Protoxide  or  black  oxide — Hg2O — is 
obtained  by  adding  a  solution  of  mercurous  nitrate  to  an  excess  of  solu- 
tion of  potassium  hydrate.  It  is  a  brownish  black,  tasteless  powder; 
very  prone  to  decomposition  into  mercuric  oxide  and  mercury.  Hydro- 
chloric acid  converts  it  into  mercurous  chloride,  and  other  acids  into  the 
corresponding  mercurous  salts. 


424  GENERAL    MEDICAL    CHEMISTRY. 

It  is  also  formed  by  the  action  of  calcium  hydrate  upon  mercurous 
compounds,  and  exists  in  the  Lotio  hydrargyri  nigra  (Br.)  or  black 
wash. 

MERCURIC  OXIDE — Red  or  binoxide — Hydrargyri  oxidum  flavum 
(U.  S.,  Br.) — Hydrargyri  oxidum  rubrum  (U.  S.,  Br.) — HgO — is  pre- 
pared by  calcining"  mercuric  nitrate  as  long  as  brown  fumes  are  given 
off;  or  by  precipitating  a  solution  of  a  mercuric  salt  by  excess  of  potas- 
sium hydrate.  The  productsvobtained  by  these  methods,  although  the 
same  in  composition,  differ  from  each  other  in  their  physical  properties 
and  in  the  activity  of  their  chemical  actions.  That  obtained  by  the  cal- 
cination of  the  nitrate,  Hydr.  oxid.  rubrum,  is  red  and  crystalline  in 
structure;  that  obtained  by  precipitation,  Hydr.  oxid..flavum,  is  yellow 
and  amorphous.  The  latter  is  much  the  more  active  in  its  chemical  and 
medicinal  actions. 

Mercuric  oxide  is  very  sparingly  soluble  in  water,  the  solution  having 
a  metallic  taste  and  an  alkaline  reaction.  It  exists  both  in  solution  and 
in  suspension  in  the  Lotio  hydrargyri  flava  (Br.)  or  yellow  wash,  pre- 
pared by  the  action  of  lime  water  upon  a  mercuric  salt. 

When  exposed  to  air  and  light  it  turns  black,  more  rapidly  in  the 
presence  of  organic  matter,  giving  off  oxygen  and  liberating  mercury.  It 
is  an  active  oxidizing  agent.  It  decomposes  the  chlorides  of  many 
metallic  elements  in  solution,  with  formation  of  a  metallic  oxide  and  of 
mercuric  oxychloride;  combines  with  the  alkaline  chlorides  to  form  soluble 
double  chlorides,  chloromer  curates  or  chlorhydrargyrates  •  and  forms 
similar  compounds  with  the  alkaline  iodides  and  bromides. 

Sulphides. — MERCUROUS  SULPHIDE  —  Hg2S  —  a  very  unstable  com- 
pound, formed  by  the  action  of  hydrogen  sulphide  upon  mercurous  salts. 

MERCURIC  SULPHIDE  —  Red  sulphide  —  Cinnabar  —  Vermilion  —  Hy- 
drargyri sulphuretum  rubrum  (U.  S.) — HgS — exists  in  nature  in  amor- 
phous red  masses  or  in  red  crystals,  and  is  the  chief  ore  of  mercury.  If 
sulphur  and  mercury  be  ground  up  together  in  the  cold,  or  if  a  solution 
of  a  mercuric  salt  be  decomposed  by  hydrogen  sulphide,  a  black  sulphide 
is  formed,  which  is  the  ^Ethiops  mineralis  of  the  older  pharmacists. 

A  red  sulphide  is  obtained  in  the  arts  for  use  as  a  pigment  (vermil- 
ion), by  agitating  for  some  hours  at  60°  a  mixture  of  mercury,  sulphur, 
potash,  and  water.  It  is  a  fine,  red  powder,  which  turns  brown,  and  finally 
black,  when  heated.  Heated  in  air  it  burns  with  formation  of  sulphur 
dioxide  and  volatilization  of  mercury.  It  is  decomposed  by  strong  sul- 
phuric acid,  but  not  by  nitric  or  hydrochloric  acids. 

Chlorides. — MERCUROUS  CHLORIDE — Protoehloride — Mild  chloride — 
Calomel — Hydrargyri  chloridum  mite  (U.S.)  —  Hydrargyri  subchlori- 
dum  (Br.) — Hg2Cl2 — is  now  principally  obtained  by  the  mutual  decompo- 
sition of  sodium  chloride  arid  mercurous  sulphate.  Mercuric  sulphate  is 
obtained  by  heating  together  2  parts  of  mercury  and  3  parts  of  sulphuric 
acid;  this  is  then  caused  to  combine  with  an  equal  amount  of  mercury  to 
that  first  used,  to  form  mercurous  sulphate;  which  is  mixed  with  dried 
sodium  chloride,  and  the  mixture  heated  in  glass  vessels,  connected  with 
condensing  chambers. 

In  practice,  varying  quantities  of  mercuric  chloride  are  also  formed, 
and  must  be  removed  from  the  product  by  washing  with  boiled,  distilled 
water  until  the  washings  no  longer  precipitate  with  ammonium  hydrate. 
The  presence  of  mercuric  chloride  in  calomel  may  be  detected  by  the  for- 
mation of  a  black  stain  upon  a  bright  iron  surface,  immersed  in  the  cal- 
omel, moistened  with  alcohol;  or  by  the  production  of  a  black  color  by 


MERCURY.  425 

hydrogen  sulphide  in  water  which  has  been  in  contact  with  and  filtered 
from  calomel  so  contaminated. 

Calomel  is  also  formed  in  a  number  of  other  reactions:  1st,  by  the  ac- 
tion of  chlorine  upon  excess  of  mercury;  2d,  by  the  action  of  mercury 
upon  ferric  chloride;  3d,  by  the  action  of  hydrochloric  acid,  or  of  a 
chloride,  upon  mercurous  oxide,  or  upon  a  mercurous  salt;  4th,  by  the 
action  of  reducing*  agents,  including  mercury,  upon  mercuric  chloride. 

Calomel  crystallizes  in  nature,  and  when  sublimed,  in  quadratic 
prisms;  when  precipitated  it  is  deposited  as  a  heavy,  amorphous,  white 
powder,  faintly  yellowish,  and  producing  a  yellowish  mark  when  rubbed 
upon  a  dark  suface.  It  sublimes,  without  fusing,  between  420°  and 
500°;  is  insoluble  in  cold  water  and  in  alcohol;  soluble  in  boiling  water 
to  the  extent  of  1  part  in  12,000;  when  boiled  with  water  for  some  time, 
it  suffers  partial  decomposition,  mercury  is  deposited  and  mercuric  chlor- 
ide dissolves. 

When  exposed  to  light,  calomel  becomes  yellow,  then  gray,  owing  to 
partial  decomposition,  with  liberation  of  mercury  and  formation  of  mer- 
curic chloride.  Chlorine  and  aqua  regia  readily  convert  it  into  mercuric 
chloride.  Iodine,  in  the  presence  of  water,  converts  it  into  a  mixture  of 
mercuric  iodide  and  chloride.  Hydrochloric  acid  and  alkaline  dblorides 
convert  it  into  mercuric  chloride.  This  change  occurs  in  the  stomach 
when  calomel  is  taken  internally,  and  that  to  such  an  extent  when  large 
quantities  of  chlorides  are  taken  with  the  food,  that  calomel  cannot  be 
used  in  naval  practice  as  it  may  be  with  patients  who  do  not  subsist  upon 
salt  provisions.  Potassium  iodide  converts  it  into  mercurous  iodide, 
which  is  then  decomposed,  by  an  excess  of  alkaline  iodide,  into  mercuric 
iodide,  which  dissolves,  and  mercury.  Solutions  of  the  sulphates  of  so- 
dium, potassium,  and  ammonium  dissolve  notable  quantities  of  calomel. 

The  hydrates  and  carbonates  of  sodium  and  potassium  decompose 
it  with  formation  of  mercurous  oxide,  which  is  decomposed  into  mercuric 
oxide  and  mercury;  if  alkaline  chlorides  be  also  present,  they  react  upon 
the  mercuric  oxide,  thus  produced,  with  formation  of  mercuric  chloride. 

MERCURIC  CHLORIDE — Perchloride  or  bichloride —  Corrosive  sublimate 
— Hydrargyri  chloridum  corrosivum  (U.  S.) — Hy drargyri  perchloridum 
(Br.) — HgCla — is  prepared  by  heating  a  mixture  of  5  parts  of  dry  mer- 
curic sulphate  with  5  parts  of  dry  sodium  chloride  and  1  part  of  manga- 
nese dioxide  in  a  glass  vessel  communicating  with  a  condensing  chamber. 

It  crystallizes  by  sublimation  in  rectangular  octahedra,  and  by 
evaporation  of  its  solutions  in  flattened,  right  rhombic  prisms;  fuses  at 
about  265°,  and  boils  at  about  295°;  100  parts  of  water  dissolve  6.57 
parts  of  mercuric  chloride  at  10°,  and  53.96  parts  at  100°;  cold  alcohol 
dissolves  it  to  the  extent  of  40  per  cent,  of  its  weight.  It  is  also  soluble 
in  ether,  and  very  soluble  in  hot  hydrochloric  acid,  which  latter  solution 
gelatinizes  on  cooling.  Its  solutions  have  a  disagreeable,  acid,  styptic 
taste,  and  are  highly  poisonous. 

It  is  easily  reduced  to  calomel  and  elementary  mercury,  and  its  aque- 
ous solutions  are  so  decomposed  when  exposed  to  light,  a  change  which 
is  retarded  by  the  presence  of  sodium  chloride.  When  heated  with  mer- 
cury it  is  converted  into  mercurous  chloride.  Zinc,  cadmium,  nickel,  iron, 
lead,  copper,  and  bismuth  remove  a  part  or  all  of  its  chlorine,  with  separa- 
tion of  calomel  or  of  mercury,  when  they  are  heated  with  dry  mercuric 
chloride  or  with  its  solution.  Hydrogen  sulphide  decomposes  it  with 
separation  of  a  yellow  sulpho-chloride,  which,  with  an  excess  of  the  gas,  is 
converted  into  the  black  mercuric  sulphide.  It  is  soluble  without  decom- 


426  GENERAL    MEDICAL    CHEMISTRY. 

position  in  sulphuric,  nitric,  and  hydrochloric  acids.  Hydrates  of  sodium 
and  potassium  decompose  it,  with  separation  of  a  reddish  brown  oxychlo- 
ride  if  added  in  sufficient  quantity,  or  of  the  orange-colored  mercuric  ox- 
ide if  an  excess  of  the  precipitant  be  used.  The  hydrates  of  calcium  and 
magnesium  effect  a  similar  decomposition,  which  does  not,  however,  take 
place  in  the  presence  of  an  alkaline  chloride  or  of  certain  organic  matters, 
such  as  sugar  and  gum.  Many  organic  substances  decompose  it  into 
calomel  and  mercury,  especially  under;the  influence  of  sunlight.  Albu- 
men forms  with  it  a  white  precipitate,  which  is  insoluble  in  water,  but 
soluble  in  an  excess  of  fluid  albumen  and  in  solutions  of  alkaline  chlorides. 
It  readily  combines  with  metallic  chlorides  to  form  soluble  double  salts, 
or  chloromercurates.  One  of  these,  obtained  in  flattened,  rhombic  prisms 
by  the  cooling  of  a  boiling  solution  of  mercuric  chloride  and  ammonium 
chloride,  has  the  composition  HgCl2,2(NH4Cl)-h  Aq.,  and  was  formerly 
known  as  sal  alembroth  or  sal  sapientice. 

MEECLTEAMMONIUM  CHLORIDE  —  Mercury  chloramidide  —  Infusible 
white  precipitate — Ammoniated  mercury — Hydrargyrum  ammoniatum 
(U.  S.,  Br.) — NH2HgCl — is  prepared  by  adding  a  slight  excess  of  ammo- 
nium hydrate  solution  to  a  solution  of  mercuric  chloride.  It  is  a  white 
powder,  insoluble  in  alcohol,  ether,  and  cold  water;  decomposed  by  hot 
water  with  separation  of  a  heavy,  yellow  powder.  It  is  entirely  volatile 
without  fusion.  The  fusible  white  precipitate  is  formed  in  small  crystals 
when  a  solution  containing  equal  parts  of  mercuric  chloride  and  ammo- 
nium chloride  is  decomposed  by  sodium  carbonate.  It  is  mercurdiammo- 
nium  chloride,  NH2HgCl,NH;Cl. 

Iodides. — MEECUEOUS  IODIDE — Protoiodide  or  yellow  iodide — Hy- 
drargyri iodidum  viride  (U.  S.,  Br) — Hg2I2 — is  prepared  by  grinding 
together  200  parts  of  murcury  and  127  parts  of  iodine  with  a  little  alco- 
hol until  a  green  paste  is  formed.  It  is  a  greenish  yellow,  amorphous 
powder,  insoluble  in  water  and  in  alcohol.  When  heated  it  turns  brown 
and  volatilizes  completely.  When  exposed  to  light,  or  even  after  a  time 
in  the  dark,  it  is  decomposed  into  mercuric  iodide  and  mercury.  The 
same  decomposition  is  brought  about  instantly  by  potassium  iodide;  more 
slowly  by  solutions  of  alkaline  chlorides  and  by  hydrochloric  acid  when 
heated.  Ammonium  hydrate  dissolves  it  with  separation  of  a  gray  pre- 
cipitate. 

MEECUEIC  IODIDE — Biniodide  or  red  iodide — Hydrargyri  iodidum 
nibrum  (U.  S.,  Br.) — HgI2 — is  obtained  by  double  decomposition  between 
mercuric  chloride  and  potassium  iodide,  care  being  had  to  avoid  too  great 
an  excess  of  the  alkaline  iodide,  that  the  soluble  potassium  iodhydrargy- 
rate  may  not  be  formed. 

It  is  sparingly  soluble  in  water;  with  alcohol  forms  colorless  solutions. 
It  dissolves  readily  in  many  dilute  acids  and  in  solutions  of  ammoniacal 
salts,  alkaline  chlorides,  and  mercuric  salts;  and  in  solutions  of  alkaline 
iodides.  Iron  and  copper  convert  it  into  mercurous  iodide,  then  into  mer- 
cury. The  hydrates  of  potassium  and  sodium  decompose  it  into  oxide  or 
oxyiodide,  and  combine  with  another  portion  to  form  iodhydrargyrates, 
which  dissolve.  Ammonium  hydrate  separates  from  its  solution  a  brown 
powder,  and  forms  a  yellow  solution  which  deposits  white  flocks. 

Cyanides. — MEECUEIC  CYANIDE — Hydrargyri  cyanidum  (U.  S.) — 
Hg(ON)2 — is  best  prepared  by  heating  together,  for  a  quarter  of  an  hour, 
potassium  ferrocyanide,  1  part;  mercuric  sulphate,  2  parts;  and  water  8 
parts.  It  crystallizes  in  quadrangular  prisms;  soluble  in  8  parts  of  cold 
water,  much  less  soluble  in  alcohol j  highly  poisonous.  When  heated  dry 


MERCURY.  427 

it  blackens,  and  is  decomposed  into  cyanogen  and  mercury;  if  heated  in 
the  presence  of  moisture  it  yields  hydrocyanic  acid,  mercury,  carbon  di- 
oxide, and  ammonia.  Hot,  concentrated  sulphuric  acid,  and  hydrochloric, 
hydrobromic,  hydriodic,  and  sulphydric  acids  in  the  cold,  decompose  it 
with  liberation  of  hydrocyanic  acid.  It  is  not  decomposed  by  alkalies. 

Salts. — NITRATES. — There  exist,  beside  the  normal  mercurous  and  mer- 
curic nitrates,  (NO3)2(Hg2)  and  (NO3)2Hg,  three  basic  mercurous  nitrates, 
three  basic  mercuric  nitrates,  and  a  mercuroso-mercuric  nitrate. 

Mercurous  nitrate — (N03)2(Hg2)  +  2Aq. — is  formed  when  excess  of 
mercury  is  digested  with  nitric  acid,  diluted  with  one-half  vol.  of  water, 
until  short,  prismatic  crystals  separate. 

It  effloresces  in  air;  fuses  at  70°;  dissolves  in  a  small  quantity  of  hot 
water,  but  with  a  larger  quantity  is  decomposed  with  separation  of  a 
yellow  basic  trimercuric  nitrate,  (NOa)2Hg,2HgO+Aq. 

The  dimercurous  nitrate — (NO3)2(Hg2),Hg2O  + Aq. — is  formed  by  act- 
ing upon  the  preceding  salt  with  cold  water  until  it  turns  lemon-yellow; 
or  by  extracting  with  cold  water  the  residue  of  evaporation  of  the  pro- 
duct obtained  by  acting  upon  excess  of  mercury  with  concentrated  nitric 
acid. 

A  trimercurous  nitrate — (NO3)4(Hg2)2,Hg2O  +  3Aq. — is  obtained  in 
large,  rhombic  prisms,  when  excess  of  mercury  is  boiled  with  nitric  acid, 
diluted  with  5  parts  of  water,  for  five  to  six  hours,  the  loss  by  evaporation 
being  made  up  from  time  to  time. 

Mercuric  nitrate — (NO3)2Hg — is  formed  when  mercury  or  mercuric 
oxide  is  dissolved  in  excess  of  nitric  acid,  and  the  solution  evaporated  at  a 
gentle  heat.  A  sirupy  liquid  is  obtained,  which,  over  quick-lime,  deposits 
large,  deliquescent  crystals,  having  the  composition  2[(NO3)3Hg]-j-Aq., 
while  there  remains  an  uncrystallizable  liquid,  (NO3)2Hg  +  2Aq. 

This  salt  is  soluble  in  water  and  exists  in  the  Liq.  hydrargyri  nitratis 
(U.  S.)  or  Liqt  hydrargyri  nitratis  acidus  (Br.);  in  the  volumetric  stan- 
dard solution  used  in  Liebig's  process  for  urea;  and  probably  in  citrine 
ointment,  Uhguentum  hydrargyri  nitratis  (U.  S.,  Br.). 

Dimercuric  nitrate — (NO3)3Hg,HgO  + Aq. — is  formed  when  mercuric 
oxide  is  dissolved  to  saturation  in  hot  nitric  acid,  diluted  with  its  volume 
of  water.  It  crystallizes  on  cooling  in  needles;  is  decomposed  by  water 
into  trimercuric  nitrate,  (NO3)2Hg.2HgO,  and  neutral  mercuric  nitrate. 

A  hexamercuric  nitrate — (NO3)2Hg,5HgO — is  also  formed,  as  a  red 
powder,  by  the  action  of  water  upon  trimercuric  nitrate. 

Sulphates. — MERCUROUS  and  MERCURIC  SULPHATES — SO4(Hg2)  and 
SO4Hg — are  crystalline  compounds,  which  are  formed  as  a  step  in  the 
preparation  of  mercurous  and  mercuric  chlorides  (q.  v.). 

Analytical  characters. — MERCUROUS. — Hydrochloric  acid,  white 
precipitate,  insoluble  in  water  and  in  acids,  except  aqua  regia;  turns 
black  on  the  addition  of  ammonium  hydrate;  when  boiled  with  hydro- 
chloric acid,  deposits  mercury,  while  mercuric  chloride  dissolves.  Hydro- 
gen sulphide,  black  precipitate,  insoluble  in  alkaline  sulphides,  in  dilute 
acids,  and  in  potassium  cyanide;  partly  soluble  in  boiling  nitric  acid. 
Potassium  hydrate,  black  precipitate,  insoluble  in  excess.  Potassium 
iodide,  greenish  precipitate,  converted  by  excess  into  mercury,  which 
remains,  and  mercuric  iodide,  which  dissolves. 

MERCURIC. — Hydrogen  sulphide,  black  precipitate.  If  the  reagent 
be  slowly  added,  the  precipitate  is  first  white,  then  orange,  finally  black. 
Ammonium  sulphydrate,  black  precipitate,  insoluble  in  excess,  except  in 
the  presence  of  organic  matter.  Potassium  or  sodium  liydrate,  yellow 


428  GENERAL    MEDICAL    CHEMISTRY. 

precipitate,  insoluble  in  excess.  Ammonium  hydrate,  white  precipitate, 
soluble  in  great  excess,  and  in  solutions  of  ammoniacal  salts.  Potassium, 
carbonate,  red  precipitate.  Potassium  iodide,  yellow  precipitate,  rapidly 
turning  to  salmon-colored,  then  to  red;  readily  soluble  in  excess  of  pre- 
cipitant or  in  great  excess  of  mercuric  salt. 

Action  on  the  economy. — Mercury,  in  the  metallic  form,  is  without 
action  upon  the  animal  economy  so  long  as  it  remains  such;  on  contact, 
however,  with  alkaline  chlorides  it  is  Converted  into  a  soluble  double 
chloride,  and  this  the  more  readily  the  greater  the  degree  of  subdivision 
of  the  metal.  The  mercurials  insoluble  in  dilute  hydrochloric  acid  are 
also  inert  until  they  are  converted  into  soluble  compounds. 

Mercuric  chloride,  a  substance  into  which  many  other  compounds  of 
mercury  are  converted  when  taken  into  the  stomach  or  applied  to  the 
skin,  not  only  has  a  distinctly  corrosive  action,  by  virtue  of  its  tendency 
to  unite  with  albuminoids,  but  when  absorbed  it  produces  well-marked 
poisonous  effects,  somewhat  similar  to  those  of  arsenical  poisoning; 
indeed,  owing  to  its  corrosive  action  and  to  its  greater  solubility,  and 
more  rapid  absorption,  it  is  a  more  dangerous  poison  than  arsenic  triox- 
ide.  In  poisoning  by  corrosive  sublimate,  the  symptoms  begin  sooner  after 
the  ingestion  of  the  poison  than  in  arsenical  poisoning,  and  those  phe- 
monena  referable  to  the  local  action  of  the  toxic  are  more  intense. 

The  treatment  should  consist  in  the  administration  of  white  of  egg, 
not  in  too  great  quantity,  and  the  removal  of  the  compound  formed,  by 
emesis,  before  it  has  had  time  to  redissolve  in  the  alkaline  chlorides  con- 
tained in  the  stomach. 

Absorbed  mercury  tends  to  remain  in  the  system  in  combination  with 
albuminoids,  from  which  it  may  be  set  free,  or,  more  properly,  brought 
into  soluble  combination,  at  a  period  quite  removed  from  the  date  of  last 
administration,  by  the  administration  of  alkaline  iodides. 

Mercury  is  eliminated  principally  by  the  saliva  and  urine,  in  which  it 
may  be  readily  detected.  The  fluid  is  faintly  acidulated  with  hydro- 
chloric acid,  and  in  it  is  immersed  a  short  bar  of  zinc,  around  which  a 
spiral  of  dentist's  gold- foil  is  wound  in  such  a  way  as  to  expose  alternate 
surfaces  of  zinc  and  gold.  After  24  hours,  if  the  saliva  or  urine  contain 
mercury,  the  gold  will  be  whitened  by  amalgamation;  and,  if  dried  and 
heated  in  the  closed  end  of  a  small  glass  tube,  will  give  off  mercury, 
which  condenses  in  globules,  visible  with  the  aid  of  a  magnifier,  in  the 
cold  part  of  the  tube. 


WEIGHTS    AND    MEASURES. 


429 


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INDEX. 


ACENAPHTHALENE,  337 

Aceta,  187 

Acetamide,  208 

Acetone,  204 

Acetones,  154 

Acetyl  hydrate,  185 
hydride,  200 
methylide,  204 

Acetylene,  287 

Acid,  acetic,  185 
aconitic,  291 
acrylic,  224 
adipic,  253 
allantoic,  272 
allanturic,  272 
amalic,  355 
amidoacetic,  208 
amidobutyric,  214 
amido  apioic,  214 
amidopropionic,  214 
amidovalerianic,  214 
amyl  sulphuric,  199 
angelic,  225 
aracha'ic,  280 
arachic,  193 
arsenic,  121,  125 
arsenious,  118,  121 
aspartic,  277 
auric,  874 
azelaic,  254 
benic,  193 
benostearic,  193 
benzoic,  297,  326 
benzoglycolic,  327 
binitrobenzoic,  327 
bismuthic,  389 
boracic,  140 
boric,  140 
bromic,  78 
butylformic,  191 
butyric,  189 
cachoutannic,  345 
caffeic,  345 
caffetannic,  345 
camphic,  296 
campholic,  296 
capric,  192 
caproic,  191 


Acid,  caprylic,  192 
carbamic,  274 
carbolic,  320 
carbonic,  234 
carminic,  342 
cathartic,  342 
cerotic,  193 
chenocholic,  212 
chenotaurocholic,  212 
chloric,  76 
chlorous,  76 
cholalic,  212 
choleio,  211 
cholesteric,  335 
cholic,  210,  212 
cbolonic,  211 
chromic,  375 
cinnamic,  297,  336 
citracouic,  291 
citric,  291 
cocinic,  280 
cocostearic,  280 
cresylic,  322 
crotonic.  225 
cyanic,  341 
cyanuric,  258 
decylic,  192 
delphinic,  191 
deoxyglutanic,  253 
dextrotartaric,  290 
dichloracetic,  187 
dichromic,  375 
digallic,  345 
digitallic,  343 
dilactic,  249 
disulphanilic,  333 
disulphuric,  92 
ditartaric,  291 
dithiouic,  92 
elaidic,  226 
erythroglucic,  289 
ethalic,  193 
ethyldiacetic,  204 
ethylenolactic,  247 
ethyloxalic,  198 
ethyl  sulphuric,  196 
fluoric,  70 
formic,  184 


432 


INDEX. 


Acid,  gadinic,  283 
gallic.  320 
gallotannic,  344 
glucic,  300 

glycerophosphoric,  286 
glycocholic,  210 
glycolamic,  208 
glycolic,  246 
hemiraellitic,  329 
hemipinic,  352 
heptylic,  192 
hexylic,  191 
hippuric,  327 
hysenic,  193 
hydrobromic,  77 
hydrochloric,  72 
hydrocyanic,  339 
hydroferricyanic,  342 
hydroferrocyanic,  342 
hydrofluoric,  69 
hydrotiuosilicic,  372 
hydriodic,  80 
hydromellitic,  330 
hj'drosulphuric,  84 
hydrosulphurous,  88 
hydurilic,  268 
hyocholic,  212 
hyoglycocholic,  212 
hyotaurocholic.  212 
hypobromous,  78 
hypochloric,  76 
hypochlorous,  78 
hypogaic,  280 
hypouitric,  100 
hyponitrous,  102 
hypophosphorous,  112 
hyposulphuric,  92 
hyposulphurous,  92 
iodic,  81 
isethionic,  231 
isobutyric,  190 
isophthalic,  328 
itaconic,  291 
lactic,  247 
laevotartaric,  290 
lauric,  192 
laurostearic,  192 
leucic,  215 
linoleic,  281 
lithic,  268 
maleic,  277 
malic,  276 
malonic,  252 
mannitic,  298 
margaric,  193 
meconic,  350,  353 
melassic,  300 
melissic,  193 
mellitic,  3:JO 
mellophanic,  330 
mesitylenic,  329 
metaboric,  140 
metantimonic,  135 
metantimonous,  135 
metaphosphoric,  114 
metarseuic,  122 


Acid,  metastannic,  391 
methylcrotonic,  226 
monochloracetic,  187 
morintannic,  345 
mucic,  298 
muriatic,  72 
myristic,  192     . 
nitric,  102 
nitrobenzoic,  327 
'.    nitrosonitric,  104 
nitrous,  102 
nonylic,  192 
Nordhausen,  92 
octylic,  192 
oenanthylic,  192 
oleic,  226 

orthoantimonic,  135 
orthoarsenic,  121 
orthoboric,  140 
orthophosphoric,  113 
osinic,  373 
oxalic,  250 
oxalovinic,  198 
oxaluric,  272 
oxamic,  274 
oxybenzoic.  329 
palmitic,  193 
parabanic,  271 
paralactic,  248 
paramucic,  298 
pelargonic,  192    • 
pentathionic,  93 
perbromic,  78 
perchloric,  76 
periodic,  81 
phenic,  320 
phenylsulphurous,  316 
phocenic,  191 
phosphoraolybdic,  347 
phosphoric,  113 
phosphorous,  112 
phosphotungstic,  373 
phosphovinic,  195 
phthalic,  328 
picric,  321 
pimelic,  253 
pivalic,  191 
plumbic,  386 
pneumic,  230 
prehnitic,  330 
propionic,  189 
propylacetic,  191 
protocatechuic,  345 
prussic,  339 
pyroantimonic,  135 
pyroarsenic.  122 
pyrobismuthic,  389 
pyroboric,  140 
pyrouallic,  325 
pyroligneous,  185 
pyromellitic,  330 
pyromucic,  298 
pyrophosphoric^  113 
pyrosulphuric,  92 
pyrotartaric,  291 
pyruvic,  291 


INDEX. 


433 


Acid,  quinic,  353 

quinotannic,  345 

quinovic,  353 

racemic,  290 

rocellic,  254 

rosolic,  321 

saccharic,  298 

salicylous,  331 

salicylic,  329 

santonic,  344 

sarcolactic,  247 

sebacic,  254 

silicotungstic,  373 

stannic,  391 

stearic,  193 

suberic,  253,  281 

succinic,  253 

sulphanilic,  333 
•       sulphobenzoic,  327 

sulphocarbonic,  245 

sulphocyanic,  341 

sulphoglucic,  300 

sulphovinic,  196 

sulphuric,  88 

sulphurous,  86 

sulphydric,  84 

tannic,  344 

tartaric,  290 

tartralic,  291 

taurocarbamic,  230 

taurocholic,  211 

terephthalic,  328 

tetraboric,  140 

tetrathionic,  93 

trichloracetic,  187 

trichroraic,  375 

trimellitic,  329 

trimesitic,  329 

trinitrophenic,  321 

trithionic,  93 

ulmic,  300 

uric,  268 

urous,  272 

valerianic,  190 
Acids,  17,  154 

amido,  156,  208 

biHary,  210 

fatty,  183 

monobasic,  153,  183 

valerianic,  190  , 
Aconitine,  360 
Acrolein,  ?24 
Action  of  acetic  acid,  188 

of  alcohol,  172 

of  ammonia,  411 

of  antimony,  137 

of  arsenic,  124 

of  barium,  415 

of  bismuth,  390 

of  bromine,  77 

of  carbon  dioxide,  240,  244 

of  carbon  monoxide,  235 

of  chloral,  202 

of  chloroform,  165 

of  chromium,  376 

of  copper,  422 
28 


Action  of  hydrochloric  acid,  75 

of  hydrocyanic  acid,  340 

of  hydrogen  sulphide,  85 

of  iodine,  79 

of  lead,  387 

of  mercury,  428 

of  nitric  acid,  104 

of  nitrogen  monoxide,  99 

of  nitrogen  tetroxide,  101 

of  oxalic  acid,  251 

of  phosphoric  acids,  115 

of  phosphorus,  108 

of  potassium,  406 

of  silver,  408 

of  sodium,  406 

of  sulphur  dioxide,  87 

of  sulphuric  acid,  91 

of  zinc,  419 
Addition,  149 
After-damp,  158 
Air,  95 

ammonia  in,  97 

confined,  237 

solids  in,  97 

water  in,  96 
Alanine,  214 
Albumin,  acid,  366 

alkali,  365 

egg,  362 

in  urine,  362 

serum,  362 

vegetable,  363 
Albuminates,  365 
Albuminoids,  360 
Albuminose,  366 
Alcohol,  169 

absolute,  172 

allylic,  221 

benzoic  318.  £ 23 

camphyl,  29  (3 

cerylic,  180 

cetylic,  180 

cholesteric,  335 

cinnamic,  334 

ethylic,  169 

isopropylic,  178 

mannitic,  298 

mellissic,  180 

menthylic,  297 

methylic,  168 

myricic,  180 

propylic,  178 

styrolic,  334 

vinic,  169 

Alcoholic  radicals,  149 
Alcohols,  150 

amylic,  152,  179 

aromatic,  323 

butyric,  178 

diatomic,  150,  230 

monoatomic,  150,  167 

pentatomic,  292 

primary,  151 

secondary,  151 

tertiary,  151 

tetratomic,  289 


434 


INDEX. 


Alcohols,  triatonaic,  150,  274 
Aldehyde,  171 

acetic,  200 

anisic,  331 

benzoic,  330 

campholic,  296 

caprylic,  203 

cinnaraic,  336 

cuminic,  331 

salicylic.  331 
Aldehydes,  154,  200 
Aldol,  225 
Ale,  175 

Algaroth,  powder  of,  135 
Alizarin,  338 
Alkaline  metals,  393 
Alkaloids,  346 

cinchona,  353 

detection  of,  348 

fixed,  350 

opium,  350 

strychnos,  356 

volatile,  349 
Alkarsin,  219 
Alantom,  272 
Allotropy,  30 
Alloxan,  272 
Allyl,  221 

hydrate,  221 

iodide,  221 

oxide,  222 

sulphide,  222 

eulphocyanate,  222 
Allylene,  288 
Allylic  series,  220 
Alphenols,  324 
Alumina,  382 
Aluminates,  382 
Aluminium,  381 

acetate,  384 

chloride,  382 

hydrate,  382 

oxide,  382 

salts,  382 
Alums,  383 
Amanitine,  207 
Amides,  156 
Amido  acids,  156 

benzol,  332 
Amines,  155,  332 
Ammonia,  98 

Ammonias,  compound,  155 
Ammonium,  408 

acetate,  410 

bromide,  409 

carbonates,  410 

chloride,  409 

compounds,  408 

hydrate,  409 

iodide,  410 

nitrate,  410 

oxide,  409 

purpurate,  269 

salts,  410 

sulphates,  410 

sulphides,  409 


Ammonium,  urates,  269 
Amorphism,  28 
Amygdalin,  342 
Amyl  acetate,  199 

chloride,  162 

nitrate,  198 

nitrite,  199 

sulphates,  199 
Amjlene,  229 
Amyloid,  367 
Amyloses,  299,  310 
Amyl  am,  310 
Analytical  characters  of  alkaloids,  347 

of  aluminium,  384 

of  ammonium,  410 

of  antimony,  132,  138 

of  arsenic,  127 

of  barium,  415 

of  bismuth,  390 

of  bromides,  81 

of  calcium,  415 

of  chlorides,  74,  81 

of  chromium,  375 

of  cobalt,  419 

of  copper,  422 

of  gold,  374 

of  iodides,  81 

of  iron,  381 

of  lead,  387 

of  lithium,  393 

of  magnesium,  417 

of  manganese,  376 

of  mercury,  427 

of  nickel,  419 

of  nitrates,  105 

of  phosphates,  114 

of  potassium,  406 

of  silver,  408 

of  sodium,  399 

of  sulphates,  91 

of  tin,  391 

of  zinc,  419 
Anhydride,  antimonic,  134 

antimonous,  133 

arsenic,  121 

arsenious,  118 

boric,  139 

carbonic,  236 

chromic,  375 

hypochlorous,  76 

molybdic,  373 

nitric,  101 

nitrous,  100 

phosphoric.  111 

phosphorous,  111 

plumbic,  385 

silicic,  372 

sulphuric,  87 

sulphurous,  86 

tungstic,  373 
Anhydrides,  23,  154 
Aniline,  332 
Anthracene,  337 
Anthracite,  142 
Antimony,  131 

black,  131,  136 


INDEX. 


435 


Antimony,  butter  of,  135 

cinnabar,  136 

crocus  of,  136 

crude,  131 

glass  of,  136 

intermediate  oxide,  134 

liver  of,  136 

pentachloride,  136 

pentasulphide,  137 

pentoxide,  134 

protochloride.  135 

regulus  of,  181 

trichloride,  135 

trioxide,  133 

trisulphide,  136 

vermilion,  136 
Apiin,  342 
Apomorphine,  351 
Aqua  ammonise,  98,  409 

chlorinii,  71 

fortis,  102 

prima,  102 

regia,  74,  104 
Arabin,  315 
Arabinose,  315 
Arbucin,  342 
Argol,  403 
Aromatic  series,  315 
Arsenamine,  116 
Arsenia,  116 
Arsenic,  116,  125 

acids,  121 

disulphide,  122 

flour  of,  118 

oxides,  118 

pentasulphide,  123 

pentoxide,  121 

sulphides,  122,  125 

tribromide,  124 

trichloride,  123 

trifluoride,  123  • 

triiodide,  124 

trioxide,  118,  125 

trisulphide,  123 

white,  118 

Arsenical  greens,  125 
Arsines,  219 
Atom,  8,  10,  11 
Atomic  heat,  13 

theory,  8 

weight,  II 
Atomicity,  15 
Atropine,  359 
Auric  chloride,  374 
Aurin,  321 
Auripigmentum,  123 
Aurous  chloride,  374 
Azote,  95 
Azulin,  321 

BAKING-POWDERS,  404 
Balsams,  297 
Barium,  415 

chloride,  415 

hydrate,  415 

oxides,  415 


Baryta,  415 

Bases,  18 

Basicity,  17 

Bassorin,  315 

Beer,  175 

Beeswax,  199 

Benzene,  315 

Benzine,  159 

Benzol,  315 

Benzoline,  160 

Benzyl  hydrate,  323 

Benzyl  hydride,  330 

Betaine,  207 

Beverages,  alcoholic,  174 

Bile  acids,  210 

physiology,  213 

pigments,  370 
Bilifuscin,  370 
Biliprasin,  370 
Bilirubin,  370 
Biliverdin,  370 
Bismuth,  388 

hydrates,  389 

nitrate,  389 

oxides,  389 

salts,  389 
Bismuthyl,  389 

carbonate,  390 

nitrate,  389 
Black  flux,  403 
Bleaching-powder,  412 
Boiling-point,  6 
Bone,  413 

ash,  412 

black,  143 

phosphate,  412 
Borax,  398 
Borneene,  297 
Borneol,  296 
Boron,  139 

bromide,  140 

chloride,  140 

fluoride,  140 

oxide,  139 
Brandy,  178 
Bromal,  171,  202 
Bromine,  77 
Bromoform,  166 
Bromoiodoform,  167 
Brucine,  358 
Butalanine,  214 
Butter,  284 
Butyral,  203 
Butyrone,  204 


CACODYLE,  219 

Cadmium,  416 

Caesium,  393 

Caffeine,  355 

Calcium,  411 

carbonates,  414 
chloride,  411 
hydrate,  411 
oxalate,  415 
oxides,  411 


436 


INDEX. 


Calcium,  phosphates,  412 

plum  bite,  385 

salts,  412 

sulphate,  412 

urates,  269 
Calomel,  424 
Camphol,  296 
Camphor,  295 

Borneo,  296 

Japan,  295 

laurel,  295 

monobromo,  296 
Camphors,  295 
Camphrene,  296 
Caouchene,  294 
Caoutchouc,  294 
Carbamide,  257 
Carbimide,  256 
Carbinol,  168 
Carbohydrates,  299 
Carbon,  141 

compounds  of,  145 

dioxide,  236 

disulphide,  246 

monoxide,  234 

perchloride,  167 

sesquichloride,  167 

tetrabromide,  166 

tetrachloride,  166,  229 

trichloride,  167 
Carbonyl,  234 

chloride,  235 
Carmine,  273 
Casein,  gluten,  365 

milk,  364 

serum,  363,  365 
Catalysis,  181 
Cedrene,  334 
Cellulin,  314 
Cellulose,  314 
Cerasin,  315 
Cerebrin,  286 
Ceruse,  387 
Ceryl  hydrate.  180 
Cetaceum,  199 
Cetene,  197 
Cetme,  199 
Cetyl  hydrate,  180 

palmitate,  199 
Chalk,  414 
Charcoal,  143 

animal,  143 
Chemistry,  1 
China  wax,  199 
Chitin,  342 
Cholin,  206 
Chloral,  171,  200 

alcoholate,  203 

hydrate,  202 
Chlorine,  70 

monoxide,  76 

peroxide,  76 

tetroxide,  76 

trioxide,  76 
Chlorocarbon,  166 
Chloroform,  164 


Chloroiodoform,  167 
Chloromethyl,  163 
Cholesterin,  335 
Chondrigen,  367 
Chondrin,  367 
Chromium,  375 

oxides,  375 

sulphates,  375 
Chrsisene,  338 
Cicutine,  349 
Cider,  177 
Cinchonine.  355 
Cinnabar,  424 
Cinnamene,  334 
Cinnamol,  334 
Classification,  26 
Coagulated  albumins,  366 
Coal,  142 
Cobalt,  419 
Cocaine,  360 
Codeine,  352 
Coke,  143 
Colchicine,  359 
Collagen,  367 
Collodion,  314 
Colocynthin,  342 
Colophony,  293 
Combustion,  36 
Composition,  1 
Compounds,  7 
Conglutin,  365 
Conhydrm,  349 
Conicine,  349 
Conii'ne,  349 
Constitution,  23,  147 
Convolvulin,  343 
Copper,  420 

chlorides.  420 

oxides,  420 

salts,  421 
Corallin,  321 
Corrosives,  75 
Corrosive  sublimate,  425 
Cosmoline,  161 
Creasol,  322 
Creasote,  322 
Creatine,  217 
Creatinine,  217 
Cresol,  322 
Cresylol,  318,  323 
Cristallin,  332 
Crith,  34 
Crocin,  342 
Crotonol,  280 
Crotoiiylene,  288 
Crystallization,  28 
Cumene.  318 
Cupric  chloride,  421 

oxide,  420 

sulphate,  421 

sulphide,  420 
Cuprous  chloride,  420 

oxide,  420 

sulphide,  420 
Curare,  359 
Curarine,  359 


INDEX. 


437 


Cyanogen,  338 
Cymene,  296,  318 
Cymol,  318 


DAHLININ,  314 
Daturine,  359 
Decomposition,  18 
Deliquescence,  40 
Deoxidation,  34 
Dextrin,  170,  311,  313 
Dextrogyrous,  32 
Dextrose,  299 
Diallyl,  221 
Diamines,  255 
Diamond,  141 
Diastase,  170,  299 
Dibromomethyl  bromide,  166 

iodide,  167 

Dichlorethyl  chloride,  167 
Dichloromethane,  163 
Dichlormethyl  chloride,  164 

iodide,  167 
Dicyanogen,  338 
Diethylamine,  206 
Diethylia,  206 
Digitalein,  343 
Digitalin,  342 
Digitaliretin,  343 
Digitalose,  343 
Dimethyl  amine,  206 

benzene,  318 

carbinol,  178 
Dimethylia,  206 
Dimorphism,  30 
Diiodomethyl  iodide,  166 
Disocryl,  224 
Divisibility,  6 
Duboisine,  359 
Dulcite,  298 
Dulcose,  298 
Dutch  liquid,  229,  230 
Dynamite,  279 
Dyslysin,  212 


EFFLORESCENCE,  38 

Elastin,  367 

Elayl,  229 

Eleoptenes,  295 

Electro-negative,  18 

Electro-positive,  18 

Elements,  7,  12 

Emetine,  355 

Emulsion,  342 

Equations,  16 

Equivalents,  9 

Erythrine,  289 

Erythrite,  289 

Eserine,  359 

Essence  of  bitter  almonds,  319 

of  chamomile,  226 

of  mirbane,  319 
Essences,  198,  292 
Etching,  69 
Ethal,  180,  199 


Ethene,  229,  287 

chlorhydrate,  230 

chlorhydrin,  230 

chloride,  229,  230 

glycol,  231 

oxide,  231 
Ether,  181 

acetic,  197 

amyl  nitrous,  199 

ethylic,  181 

formic,  197 

hydrobromic,  162 

hydrochloric,  162 

hydriodic,  162 

methylic,  180 

muriatic,  162 

nitric,  194 

nitrous,  195 

oxalic,  198 

phosphoric,  195 

pyroacetic,  204 

sulphuric,  181 
Etherification,  181 
Etherine,  197 
Etherol,  197 
Ethers,  152 

compound,  153,  194 

haloid,  150 

mixed,  153,  188 

simple,  152,  180 
Ethyl,  149 

acetate,  197 

borates,  195 

bromide,  162 

carbinol,  178 

carbonates,  198 

chloride,  162 

formiate,  197 

hydrate,  169 

iodide,  162 

nitrate,  194 

nitrite,  195 

oxalates,  198 

oxide,  181 

sulphates,  196 

sulphide,  218 

sulphydrate,  218 
Ethylamine,  206 
Ethylene,  229 

alcohol,  231 

bichloride,  230 

glycol,  231 

hydrate,  231 

oxide,  231 
Ethylia,  206 
Eucalin,  306 
Eucalyptene,  297 
Eucalyptol,  297 


FATS,  279,  283 

phosphorized,  286 
Fermentation,  170 
Ferments,  animal,  368 
Ferric  acetates,  380 

bromide,  379 


438 

Ferric,  chloride,  379 
ferrocyanide,d«U 
hydrates,  126,  378 
iodide,  379 
nitrates,  379 
oxide,  378 
phosphate,  380  Q 
pyrophosphate,  380 
sulphates,  379 
sulphide,  378 
Ferrous  acetate,  380 
bromide,  379 
carbonate,  380 
chloride,  378 
ferricyanide,  381 
iodide,  379 
lactate,  380 
nitrate,  379 
oxalate,  380 
oxide,  378 
sulphate,  379 
sulphide,  378 
tartrate,  380 
Fibrin,  366      _ 
Fibrinogen,  363 
Fibrinoplastic  matter,  d 
Fire-damp,  157 
Fluids,  5 
Fluorene,  337 
Fluorine,  69 
Fluviale,  295 
Foods,  vegetable,  312 
Formamide,  208 
Formulae,  16 

empirical,  16 
general,  147 
graphic,  23 
of  constitution,  23 
typical,  22 
Formyl  bromide,  166 
chloride,  164 
iodide,  166 
Fraxine,  298 
Fuchsine,  333 
Furf urol,  298 
Fusel  oil,  176 
Fusing-point,  6 

GADININ,  283 
Gaduin,  283 
Galactose,  306 
Galena,  386 
Gallium,  381 
Gasoline,  160 
Gelatin,  367 

sugar  of,  208 
Gin,  178 

Glauber's  salt,  396 
Gliadin,  365 
Glonoin,  279 
Glucinium,  381 
Glucosan,  300 
Glucose,  170,  299 
Glucoses,  299 
Glucosides,  299,  342 


INDEX. 


Glycerin,  274,  275 
ethers  of,  277 
Glycin,  208 
Glycocol,  208 
Glycocols,  156 
Glycogen,  313 
Glycol,  231 

toluyl,  324 
GlycoMide,  247 
Glycols,  230 
Glycyrrhizin,  343 
Glyoxyldmrea,  272 
Gold,  374 

Grape-sugar,  170,  299 
Graphite,  142 
Guanine,  273 
Guaranine,  355 
Gum,  British,  313 
Gum  resins,  297 
Gums,  315 
Gun-cotton,  314 
Gutta,  295 

percha,  295 
Gypsum,  412 

H/EMATIN,  370 
Hsematocrystallin,'369 
Haamochromogen,  370 
Haemoglobin,  369 
Helenin,  214 
Homologous  series,  14b 
Hydrates,  18,  23 
Hydrobilirubin,  370 
Hydrocarbons,  149,  228 
first  series,  157 
second  series,  227 
third  series,  287 
fourth  series,  292 
fifth  series,  315 
sixth  series,  334 
seventh  series,  836 
eighth  series,  336 
ninth  series,  337 
tenth  s°ries,  337 
eleventh  series.  337 
higher  series,  338 
series  of,  228 
non- saturated,  227 
saturated,  149,  157 
Hydrogen,  33 

antimonide.  \6& 
arsenides,  116,  125 
bromide,  77 
chloride,  72 
dioxide,  67 
fluoride,  69 
heavy  carburetted,  229 
iodide,  80 

light  carburetted,  157 
nitride,  98 
oxide,  37 
peroxide,  67 
phosphides,  110 
silicide,  372 
sulphide,  84 


INDEX. 


439 


Hydroquinone,  324 
Hygrometers,  96 
Hyoscyamine,  359 
Hypoxanthine,  273 


IGASURINE,  359 

Illuminating  gas,  287 

Indican,  371 

Indiglucin,  371 

Indigogen,  371 

Indium,  381 

Inosite,  306 

Inulin,  305,  314 

lodal,  203 

Iodine,  78 

lodoform,  166 

Tridium,  392 

Iron,  378 

acetates,  380 
bromides,  379 
carbonate,  380 
chlorides,  378 
ferricyanide,  381 
ferrocyanide.  380 
hydrates,  378 
iodides,  379 
lactate,  380 
nitrates,  379 
oxides,  378 
phosphates,  379 
pyrophosphate,  380 
salts,  379 
sulphates,  379 
sulphides,  378 
tartrates,  380 

Isethionamide,  230 

Isodulcite,  343 

Isomerism,  147 

Isomorphism,  29 

Isoprene,  294 

Ivory  black,  143 


JALAPIN,  343 
James'  powder,  134 
Javelle  water,  401 
Jet,  142 


KAOLIN,  383 
Kelp,  78 
Keratin,  367 
Kerosene,  160 
Ketone,  204 
Ketones,  154 
King's  yellow,  123 
Kyanol,  332 


LACTINE,  309 
Lactose,  309 
Lsevogyrous,  32 
Laevulosan,  305 
LjBvulose,  305 
Lamp-black,  143 


Lard,  284 
Latent  heat,  6 
Laughing-gas,  99 
Laurene,  318 
Law  of  Ampere,  10 

Avogadro,  10 

definite  proportions,  7 

Dulong  and  Petit,  13 

multiple  proportions,  8 
Laws  of  Dalton,  7 

Gay  Lussac,  9 
Lead.  384 

acetates,  387 

black,  142 

carbonate,  387 

chlorides,  386 

chromate,  387 

dioxide,  386 

glycocholate,  211 

iodide,  386 

monoxide,  386 

nitrate,  386 

oxides,  386 

peroxide,  386 

protoxide,  886 

puce  oxide,  386 

red,  386 

salts,  386 

sulphates,  386 

sulphide,  386 
Lecithin,  286 
Lecithins,  206 
Legumin,  365 
Lethal,  199 
Leucine,  214 
Lichenin,  315 
Lignin,  314 
Lime,  411 

chloride  of,  412 

water,  411 
Liqueurs,  178 
Litharge,  385 
Lithium,  393 

bromide,  393 

carbonate,  393 

chloride,  393 

hydrate,  393 

oxide,  393 

salts,  393 

urates,  269,  393 


MACLURIN,  345 

Magenta,  333 

Magnesia,  416 
alba,  417 

Magnesium,  416 
carbonates,  417 
chloride,  416 
hydrate,  416 
oxide,  416 
phosphates,  416 
salts,  416 
silicates,  417 
sulphate,  416 

Malt,  170 


440 


INDEX. 


Maltose,  309 
Manganese,  376 

oxides,  376 

salts,  376 
Mannite,  298 
Mannitose,  306 
Marsh-gas,  157 
Massicot,  385 
Mauvein,  334 
Meconine,  350 
Melampyrine,  298 
Melanin,  371 
Melezitose,  310 
Mellite,  330 
Melissin,  199 
Melitose,  309 
Menthol,  297 
Menyanthin,  314 
Mercaptan,  218 
Mercaptides,  218 
Mercuric  chloride,  425 

cyanide,  426 

iodide,  426 

oxide,  424 

sulphide,  424 
Mercurcus  chloride,  424 

iodide,  426 

oxide,  423 
Mercury,  423 

chlorides,  424 

iodides,  426 

oxides,  423 

salts,  427 

sulphides,  424 
Mesitylene,  318 
Mesoxalylurea,  272 
Metachloral,  200 
Metallooyanides,  341 
Metalloids,  26 
Metals,  26 
Metamerism,  147 
Methal,  199 
Methene,  229 

chloride,  163 
Methenyl  bromide,  166 

chloride,  164 

iodide,  166 
Methyl  benzene,  318 

bromide,  162 

carbinol,  169 

chloride,  162 

glycocol,  209 

hydrate,  168 

hydride,  157 

iodide,  162 

nitrate,  194 

nitrite,  194 
oxide,  180 
Methylamine,  205 
Methylene,  229 

bichloride,  163 
Methylia,  205 
Milk,  363 

of  lime,  411 
Minium,  385 
Mixtures,  8 


Molecule,  7,  11 
Molybdenum,  373 
Monamides,  207 
ytonamines,  155,  205 
Monochlormethyl  chloride,  163 
Monochlorethyl  chloride,  167 
VIorphine,  351 
Mucin,  367 
Muaiexid,  269 
Muscarine,  207,  359 
Vlycose,  310 
Myosin,  363 
Myricyl  hydrate,  180 

NAPHTHA,  159 

wood,  168 
Naphthalene,  336 
Naphthydrene,  336 
Narceine,  352 
Narcotine,  352 
Nascent  state,  35 
Neurine,  206,  286 
Nickel,  419 
Nicotine,  350 
Nitre,  401 
Nitro-benzene,  316,  319 

benzol,  319 

cellulose,  314 

glycerin,  278 
Nitrogen,  94 

bromide,  106 

chloride,  106 

dioxide,  100 

iodide,  106 

monoxide,  99 

pentoxide,  101 

peroxide,  100 

protoxide,  99 

tetroxide,  100 

trioxide,  100 
Nitrous  fumes,  100 
Nomenclature,  20 

OILS,  279 

distilled,  294 

fixed,  279 

lubricating,  161 

volatile,  292,  294 
Olefiant  gas,  229 
defines.  227 
Oleoresins,  297 
Optically  active  bodies,  32 
Orcein,  324 
Orcin,  289,  324 
Organic  substances,  145 
Orpiment,  123 
Osmium,  373 
Oxalylurea.  271 
Oxamide,  274 
Oxycholine,  207 
Oxycinchonine,  355 
Oxygen,  35 
Oxyneurine,  207 
Oxyphenols,  324 
Ozone,  37 


INDEX. 


441 


PALLADIUM,  392 

Pancreatin,  368 

Paraffin,  101 

Paraffines,  149,  158 

Paraglobulin,  363 

Paramorphine,  353 

Parapeptone,  366 

Parasaccharose,  310 

Paris  green,  421 

Pearlash,  412 

Pentene,  229 

Peonin,  321 

Pepsin,  368 

Peptones,  366 

Permanent  gases,  34 

Peruvin.  334 

Petroleum,  158 

Phenicin,  321 

Phenol,  320 

benzylic,  322 
cresylic,  322 
cymylic,  323 

Phenols,  319 

Phenyl,  332 

hydrate,  315,  320 

Phenylamine,  332 

Phlorizin,  343 

Phloroglucin,  325 

Phosgene,  235 

Phosphamine,  110 

Phosphines,  219 

Phosphonia,  110 

Phosphorus,  106 
bromides,  115 
iodides,  115 
oxides,  111 
oxychloride,  115 
pentachloride,  115 
pentoxide,  111 
sulphides,  115 
trichloride,  115 
trioxide,  111 

Phycite,  289 

Physostigmine,  359 

Picnometer,  4 

Pilocarpine,  360 

Pinite,  292 

Plasmine,  363 

Plaster-of -Paris,  412 

Platinic  chloride,  392 

Platinum,  392 

Plumbago,  142 

Plumbates,  386 

Poisons,  75 

Polarimetry,  31 

Polymerism,  147 

Porcelain,  383 

Porter,  175 

Potash,  400,  402 

Potassa,  400 

Potassium,  399 
acetate,  402 
aluminate,  382 
arsenite,  125 
bichromate,  406 
bromide,  400 


Potassium,  carbonates,  403 

chlorate,  401 

chloride,  400 

chromate,  402 

cyanide,  405 

dichromate,  402 

ferricyanide,  406 

ferrocyanide,  406 

hydrate,  400 

hypochlorite,  401 

iodide,  400 

nitrate,  401 

oxalates,  403 

oxides,  400 

permanganate,  402 

pyrosulphate,  402 

salts,  401 

sulphates,  401 

sulphides,  400 

sulphites,  402 

tartrates,  402 
Potato  spirit,  179 
Proof  spirit,  172 
Propiane,  204 
Propyl  benzene,  318 

hydrate,  178 
Propylamine,  206 
Propylphyoite,  289 
Protein  bodies,  360 
Protein,  365 
Protogon,  286 
Prussian  blue,  406 
Pseudoxanthine,  268 
Psychrometers,  96 
Ptoamines,  360 
Ptyalin,  368 
Pyrene,  338 
Pyrites,  378 
Pyrocatechin,  324 
Pyrodextrin.  311 
Pyrogallol,  325 
Pyroxam,  312 
Pyroxylin,  314 


QUERCITE,  292 
Quercitrin,  843 
Quick-lime,  411 
Quinine,  353 
Quinone,  324 
Quinova  red,  345 
Quinovin,  343 


RADICALS,  17,  146 
Ratafia,  331 
Realgar,  122 
Re'duction,  34 
Resins,  297 
Resorcin,  324 
Rhigolene,  159 
Rhodium,  392 
Ricinine,  280 
Rock  crystal,  372 

oil,  158 
Rosaniline,  333 


442 


INDEX. 


Rosin,  293 
Rubidium,  393 
Ruin,  178 
Ruthenium,  392 


SACCHARIDES,  308 
Saccharoses,  299,  307 
Saffranin,  334 
Sal  ammoniac,  409 

volatile,  410 
Salseratus,  403 
Salicin,  343 
Salicylol,  331 
Saligenin,  324,  344 
Salt,  Epsom,  416 

of  lemon,  403 

of  tartar,  402 

Rochelle,  405 

Seidlitz,  416 

sorrel,  403 
Saltpetre,  401 

Chili,  396 
Santonin,  344 
Sarcine,  273 
Sarcosine,  209 
Scheele's  green,  421 
Schweinfurth  green,  421 
Sea  salt,  394 
Secalin,  206 
Selenium,  93 
Septicine,  360 
Serin,  363 
Silex,  372 
Silicates,  372 
Silicic  oxide,  372 
Silicichloroform,  372 
Silicon,  372 

chloride,  372 
Silver,  407 

bromide,  407 

chloride,  407 

cyanide,  408 

nitrate,  408 

oxides,  407 

salts,  408 
Soaps,  285 
Soda,  394,  398 
Sodium,  394 

acetate,  398 

aluminate,  382 

arsenite,  125 

borates,  398 

bromide,  395 

carbonates,  398 

chloride,  394 

glycocholate,  211 

hydrate,  394 

hypochlorite,  398 

hyposulphite,  397 

iodide,  396 

nitrate,  396 

oxides,  394 

permanganate,  398 

phosphates,  397 

salts,  396 


Sodium,  silicates,  397 

sulphates,  396 

sulphovinate,  196 

tungstate,  373 

urates,  269 
Solanine,  344,  359 
Sorbin,  306 
Spermaceti,  199 
Spirits,  171,  177 

-methylated,  169 

pyroxylic,  168 

wood,  168 

Stannic  compounds,  391 
Stannous  compounds,  891 
Starch,  310 
Stearoptenes,  295 
Steel,  378 
Stercobilin,  371 
Stethal,  199 
Stibines,  219 
Stilbene,  337 
Strontium,  411 
Strychnine,  356 
Styracin,  334 
Styrol,  334 
Styrolene,  334 
Styrone,  334 
Sucrates,  308 
Sugar,  beet,  307 

candy,  307 

cane,  307 

diabetic,  299 

of  gelatin,  208 

grape,  299 

inverted,  308 

of  lead,  387 

liver,  299 

milk,  309 

muscle,  306 

physiology  of,  300 

tests  for,  302 

uncrystallizable,  305 
Sulphethylates,  218 
Sulphobenzide,  316 
Sulphur,  82 

bromides,  93 

chlorides,  93 

dioxide,  86 

iodides,  93 

trioxide,  87 
Sulphurea,  267 
Superphosphate,  396 
Supersaturation,  412 
Synanthrose,  310 
Syntonin,  366 


TALLOW,  284 
Tannin,  344 
Tartar,  403 

emetic,  405 
Taurine,  211,  230 
Tellurium,  93 
Terebenthene,  292 
Terpine,  292,  297 
Terpinol,  297 


I^DEX. 


443 


Terra  alba,  412 
Test,  Boettger's,  303 

Fehlmg's,  303 

fermentation,  303 

Frezenius'  and  von  Babo's,  130 

Gallois',  306 

Marsh's,  117,  129,  132 

Moore's,  302 

Mulder-Neubauer's,  302 

Pettenkofer's,  212 

Piria's,  217 

Reinsch's,  127 

Scherer's,  216,  306 

Trommer's,  302 
Thebaine,  353 
Theine,  355 
Thialdine,  200 
Thymol,  323 
Tin,  390 

compounds,  391 
Tincal,  398 
Titanium,  390 
Toluene,  318 
Toluidine,  318 
Toluol,  318 
Trehalose,  310 
Tributyrin,  277 
Trichloraldehyde,  200 
Triethylamine,  206 
Triethylia,  206 
Trimargarin,  278 
Tri methyl  benzene,  318 
Trimethylamine,  206 
Trimethylia,  206 
Trimorphism,  30 
Trinitro-glycerin,  278 
Trinitro-phenol,  321 
Triolein,  278 
Tripalmitin,  278 
Triple  phosphate,  417 
Tristearin,  278 
Trivalerin,  278 
Trypsin,  369 
Tungsten,  373 
Tunicin,  314 
TurnbuU's  blue,  406 
Turpentine,  293 
Tutty,  418 
Typical  elements,  27 
Tyrosine,  216 


UREA,  257 

determination  of,  264 

nitrate,  259 

oxalate,  260 

tests  for,  263 
Ureas,  compound,  267 
Ureids,  271 
Urethan,  198 
Urinary  pigments,  371 


Urinometer.  5 
Urobilin,  370 
Uroxanthin,  371 


VALENCE,  15 
Valeral,  203 
Valerine,  229 
Varech,  78 
Vaselin,  161 
Veratrine,  359 
Verdigris,  422 
Vermilion,  424 
Vinegar,  187 

wood,  168 
Vitelin,  363 
Vitriol,  blue,  421 
green,  379 
oil  of,  89 
white,  418 


WATER,  37 

glass,  397 
hardness  of,  49 
impurities  of,  49 
mineral,  58 
oxygenated,  67 
purification  of,  57 

Weight,  absolute,  2 
apparent,  2 
atomic,  11 
molecular,  11,  14  ' 
relative,  2 
specific,  2 

Whiskey,  178 

White  lead,  387 

precipitate,  426 

Wine,  175 

oil  of,  196 
spirits  of,  169 

Wolfram,  373 

Wourara,  359 


XANTHIC  oxide,  272 
Xanthine,  272 
Xenols,  323 
Xylene,  318 
Xylenols,  323 
Xyloidin,  312 
Xylol,  318 


YEAST,  170 


ZINC,  418 

compounds  of,  418 

ethyl,  219 
Zirconium,  390 


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218871 


•^•••••B 


